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Dear Editor,
We thank Dr. Balducci and her colleagues for their interest in our paper [1]. They raise several important points regarding optic nerve angiography, and we are thankful to have the opportunity to discuss these items further.
In preparation of our manuscript, we felt that diffuse changes in the peripapillary capillary network were best appreciated at lower magnification. Balancing this objective in presentation with a sufficient resolution to appreciate the focal deficits we highlighted, the image sizes published represent what we felt was the best compromise. For those who feel that higher magnification images are needed, we have included in this letter Figure 1, which includes the same 6x6 mm OCT-A images in the acute phase for all cases in our study. Quantitation of OCT-A signal can be a powerful way to objectively assess regional as well as between eye and patient differences. We have recently performed a quantitative assessment of angiographic signal in non-arteritic anterior ischemic optic neuropathy using a different device, the Optovue Avanti (Fremont, CA) [1]. However, in the current study, the small number of affected eyes did not allow for meaningful statistical analysis of quantitative data. In addition, quantitative analyses can be misleading when confounding artifacts or segmentation errors are present as discussed below.
Jia and colleagues [2] showed a strong non-linear correlation between RNFL thickness and radial peripapillary...
Dear Editor,
We thank Dr. Balducci and her colleagues for their interest in our paper [1]. They raise several important points regarding optic nerve angiography, and we are thankful to have the opportunity to discuss these items further.
In preparation of our manuscript, we felt that diffuse changes in the peripapillary capillary network were best appreciated at lower magnification. Balancing this objective in presentation with a sufficient resolution to appreciate the focal deficits we highlighted, the image sizes published represent what we felt was the best compromise. For those who feel that higher magnification images are needed, we have included in this letter Figure 1, which includes the same 6x6 mm OCT-A images in the acute phase for all cases in our study. Quantitation of OCT-A signal can be a powerful way to objectively assess regional as well as between eye and patient differences. We have recently performed a quantitative assessment of angiographic signal in non-arteritic anterior ischemic optic neuropathy using a different device, the Optovue Avanti (Fremont, CA) [1]. However, in the current study, the small number of affected eyes did not allow for meaningful statistical analysis of quantitative data. In addition, quantitative analyses can be misleading when confounding artifacts or segmentation errors are present as discussed below.
Jia and colleagues [2] showed a strong non-linear correlation between RNFL thickness and radial peripapillary capillary density in 10 healthy subjects. That healthy subjects with normal vision and no (ischemic) posterior pole disease were analyzed is an important distinction. Indeed, there is an increase in RNFL thickness associated with ischemic optic neuropathies, but caution should be used in extrapolating trends based on normative data to the pathologic states of ischemic optic nerve disorders. In addition, arteritic anterior ischemic optic neuropathy (AAION) produces edema and is commonly associated with peripapillary cotton-wool spots that produce blockage effects, as demonstrated in cases 1-3 in our series (denoted with blue arrows) [1]. These secondary effects can alter normal anatomic boundaries and thus segmentation, which can lead to erroneous results and inaccurate conclusions in a small cohort.
With respect to the correspondence of choroidal filling defects seen on FA and OCT-A, it is important to first acknowledge that spectral domain OCT is suboptimal for imaging sub-RPE (vascular) structures due to limitations in resolution at deeper penetrance lamina [3]. Of note, we are currently collecting a series of patients with ischemic optic neuropathies imaged using swept-source OCT-A with the specific focus on choroidal vascular perfusion (Tieger et al, in preparation), though there are limitations with this approach as well. We agree that wide-field imaging may been better suited for capturing choroidal perfusion defects and have incorporated this into our imaging strategy moving forward. In the current study, we performed macular scans for some patients in addition to optic disc-centered scans in a subset of patients, including the initial presentation of case 2 (Figure 2). Fluorescein angiography revealed a clear choroidal filling defect affecting the macular region temporal to the disc and extending inferiorly (red arrow). Counter-intuitively, OCT-A showed a corresponding increase in angiographic signal in the superficial lamina and choroidal lamina (Figure 2B,D). We did not feel that the correspondence between the apparent increased choriocapillary OCT-A signal and the reduced fluorescence on FA in the area inferior to the disc (red arrows) was clear enough for publication especially in the context of other imaging limitations [3].
Balducci and colleagues [4] reported a single case of acute AAION imaged with the Optovue device and described corresponding perfusion defects on FA and OCT-A that were continuous with the optic disc. However, there are several limitations with the image presented. First, the image is confounded by motion artifact. Second, the image is too highly magnified such that the region of interest is at the edge of the sampling area, where segmentation errors can occur. Given that the retinal arterioles visible on FA are not visible in the superficial lamina on OCT-A, segmentation error is likely present, similar to case 2 in our series (Figure 3). Comparison with composite images can reveal such errors. Third, no fundus photograph is presented to exclude edema, which can impart a blockage effect as also demonstrated in case 2 in our series (Figure 2; blue arrow) [1].
In conclusion, OCT-A is a new and powerful tool for imaging microvascular anatomy in normal and pathologic conditions of the posterior pole, but OCT-A image acquisition and segmentation can be prone to artifact and misrepresentation. Balducci and colleagues highlight a number of these pitfalls in the early application of this new technology in the analysis of ischemic optic neuropathies. As the field continues to explore the application of OCT-A, it will be critical to remember that the study of the pathologic state teaches us about the technology (and limitations therein) just as the technology provides new insights into the pathophysiology.
Figures can be downloaded at the following link and will be available through 8/31/2019: https://www.dropbox.com/sh/kf1fp9gsuas4zm1/AACLiIA2cKLF_J9nkWGdymPza?dl=0
Conflicts of Interest: None
FIGURE LEGENDS
Figure 1. Enlarged Optical Coherence Tomographic Angiography (OCT-A) images (6 mmx 6 mm; Zeiss) of all controls and cases. Superficial, choriocapillary and choroidal laminar segmentations are included. The right (top) and left (bottom) eyes are included for each case, which are demarcated by red lines.
Figure 2. Enlarged and expanded OCT-A sampling regions for case 2. (A) Corresponding fluorescein angiography image (early) depicting blockage by an overlying cotton wool spot along the superior arcade (blue arrow) and choroidal hypoperfusion temporal to the optic disc most prominent inferiorly (red arrow) (represented as Figure 3H in initial report). (B-D) Superficial, choriocappilary and choroidal laminar segmented OCT-A images are included with montaged samplings centered on the optic disc and macula. Blue and red arrow represent the same regions corresponding to those in the fluorescein angiogram; the blue arrows indicate signal blockage extending through all lamina, and the red arrows indicate the region with increased OCT-A signal in the superficial and choroidal laminae. The yellow arrow denotes attenuated OCT-A signal in a region superior to the optic disc in the superficial lamina. Images are each 6 mm x 6 mm and were acquired using the Zeiss device.
Figure 3. Enlarged OCT-A images for re-presentation of case with optic disc edema and AAION. (A) Fundus photograph of the optic disc depicting pallid optic disc edema that is obscuring the peripapillary retinal arterials (blue arrow). (B,C) Composite and superficial laminar OCT-A images (3 mm x 3 mm; Optovue) for the corresponding region depicted in the fundus photograph. There is apparent retinal arterial signal attenuation in the superficial lamina (C) as denoted by the blue arrow that is partially secondary to segmentation error as it is better preserved in the composite segmentation (B; blue arrow). There is some component of blockage due to overlying edema as evident in the fundus photograph, but some regions of peripapillary OCT-A signal attenuation likely represent true hypoperfusion as they do not correspond to overlying blockage elements (for example: yellow arrow).
REFERENCES
1. Gaier ED, Gilbert AL, Cestari DM, Miller JB. Optical coherence tomographic angiography identifies peripapillary microvascular dilation and focal non-perfusion in giant cell arteritis. Br J Ophthalmol 2018;102(8):1141-46.
2. Jia Y, Simonett JM, Wang J, et al. Wide-Field OCT Angiography Investigation of the Relationship Between Radial Peripapillary Capillary Plexus Density and Nerve Fiber Layer Thickness. Invest Ophthalmol Vis Sci 2017;58(12):5188-94.
3. Diaz JD, Wang JC, Oellers P, et al. Imaging the Deep Choroidal Vasculature Using Spectral Domain and Swept Source Optical Coherence Tomography Angiography. Journal of vitreoretinal diseases 2018;2(3):146-54.
4. Balducci N, Morara M, Veronese C, et al. Optical coherence tomography angiography in acute arteritic and non-arteritic anterior ischemic optic neuropathy. Graefes Arch Clin Exp Ophthalmol 2017;255(11):2255-61.
We appreciate Dr. Taylor’s interest in our paper as well as drawing our attention to environmental factors that may influence XFS in Australian aboriginal people. Certainly, this is an area that deserves further investigation. Dr Taylor’s review article presents some interesting findings, particularly regarding the high incidence of XFS in Aboriginal individuals. (1)
Consistent with recent literature, Dr. Taylor identified a ‘latitude effect’. Interestingly however, XFS was more commonly observed at lower latitudes, which contrasts other findings of high altitude exposure associated with XFS in an American population. (2)
The recognition of solar radiation exposure as an environmental factor associated with XFS is plausible due to accumulating evidence that supports this relationship. (3) While providing some useful insights, this article justifies the lack of understanding and the need for further research on environmental factors.
1. Taylor HR. Pseudoexfoliation, an environmental disease? Trans Ophthalmol Socs UK 1979; 99: 302- 307
2. Stein JD, Pasquale LR, Talwar N, Kim DS, Reed DM, Nan B, Kang JH, Wiggs JL,Richards JE. Geographic and climatic factors associated with exfoliation syndrome. Arch Ophthalmol. 2011 Aug;129(8):1053-60.
3. Jiwani AZ, Pasquale LR. Exfoliation Syndrome and Solar Exposure: New Epidemiological Insights Into the Pathophysiology of the Disease. International ophthalmology clinics. 2015;55(4):13.
We appreciate Dr. Taylor’s interest in our paper as well as drawing our attention to environmental factors that may influence XFS in Australian aboriginal people. Certainly, this is an area that deserves further investigation. Dr Taylor’s review article presents some interesting findings, particularly regarding the high incidence of XFS in Aboriginal individuals. (1)
Consistent with recent literature, Dr. Taylor identified a ‘latitude effect’. Interestingly however, XFS was more commonly observed at lower latitudes, which contrasts other findings of high altitude exposure associated with XFS in an American population. (2)
The recognition of solar radiation exposure as an environmental factor associated with XFS is plausible due to accumulating evidence that supports this relationship. (3) While providing some useful insights, this article justifies the lack of understanding and the need for further research on environmental factors.
1. Taylor HR. Pseudoexfoliation, an environmental disease? Trans Ophthalmol Socs UK 1979; 99: 302- 307
2. Stein JD, Pasquale LR, Talwar N, Kim DS, Reed DM, Nan B, Kang JH, Wiggs JL,Richards JE. Geographic and climatic factors associated with exfoliation syndrome. Arch Ophthalmol. 2011 Aug;129(8):1053-60.
3. Jiwani AZ, Pasquale LR. Exfoliation Syndrome and Solar Exposure: New Epidemiological Insights Into the Pathophysiology of the Disease. International ophthalmology clinics. 2015;55(4):13.
We read with interest the article written by Creuzot-Garcher and colleagues that was published in the June 2018 issue of your journal. 1 The authors retrospectively reviewed billings codes from a national database in France from January 2004 to December 2014 to examine acute postoperative endophthalmitis (POE) rates. They reported an incidence of acute POE in stand-alone phacoemulsification of 0.102% over this 11-year period. In contrast, combined surgery in which phacoemulsification was performed with another intraocular procedure had an overall higher incidence of 0.149%. The incidence of acute POE in combined phacoemulsification and glaucoma surgery, corneal surgery, and vitreoretinal surgery was found to be 0.089%, 0.142%, and 0.223% respectively.
As Creuzot-Garcher and colleagues mention, many phakic patients who undergo either glaucoma surgery, corneal surgery, or vitreoretinal surgery, are elderly and likely will require cataract extraction at some point.1 In addition, it is well established that these surgeries promote cataract formation in phakic eyes, and therefore patients who do not undergo combination surgery will likely require stand-alone cataract surgery in the future.
Hence, it would be instructive to compare the risk of acute POE in combined surgery with the total risk conferred by separately performing the two surgeries. We made the assumption that the chance of endophthalmitis in each surgery is independent. Using the...
We read with interest the article written by Creuzot-Garcher and colleagues that was published in the June 2018 issue of your journal. 1 The authors retrospectively reviewed billings codes from a national database in France from January 2004 to December 2014 to examine acute postoperative endophthalmitis (POE) rates. They reported an incidence of acute POE in stand-alone phacoemulsification of 0.102% over this 11-year period. In contrast, combined surgery in which phacoemulsification was performed with another intraocular procedure had an overall higher incidence of 0.149%. The incidence of acute POE in combined phacoemulsification and glaucoma surgery, corneal surgery, and vitreoretinal surgery was found to be 0.089%, 0.142%, and 0.223% respectively.
As Creuzot-Garcher and colleagues mention, many phakic patients who undergo either glaucoma surgery, corneal surgery, or vitreoretinal surgery, are elderly and likely will require cataract extraction at some point.1 In addition, it is well established that these surgeries promote cataract formation in phakic eyes, and therefore patients who do not undergo combination surgery will likely require stand-alone cataract surgery in the future.
Hence, it would be instructive to compare the risk of acute POE in combined surgery with the total risk conferred by separately performing the two surgeries. We made the assumption that the chance of endophthalmitis in each surgery is independent. Using the data presented by Creuzot-Garcher, we found the following:
(i) In the scenario where glaucoma surgery is performed and, at a separate date cataract surgery is done, the total risk of developing acute POE would be 0.171%. This is higher than the risk of 0.089% in combined surgery quoted in the article.
(ii) In the scenario where corneal surgery is performed and, at a separate date cataract surgery is done, the total risk of developing acute POE would be 0.236%. This is higher than the risk of 0.142% in combined surgery quoted in the article.
(iii) In the scenario where vitreoretinal surgery is performed and, at a separate date cataract surgery is done, the total risk of developing acute POE would be 0.292%. This is higher than the risk of 0.223% in combined surgery.
Hence, while combined surgery may be associated with a higher incidence of acute POE as compared to a stand-alone procedure, multiple surgeries on the same eye but performed at different sittings may yield an overall higher risk. This information should be taken into consideration when planning surgery in phakic eyes.
R. Rishi Gupta MD, FRCSC1
Mark E. Seamone MD, FRCSC2
Marcelo Nicolela MD, FRCSC1
Jayme Vianna MD1
Daniel O’Brien MD, FRCSC1
1 Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, NS, Canada
2 Department of Ophthalmology, University of Alberta, Edmonton, AB, Canada
References:
1. Creuzot-Garcher CP, Mariet AS, Benzenine E, Daien V, Korobelnik JF, Bron AM, Quantin C. Is combined cataract surgery associated with acute postoperative endophthalmitis? A nationwide study from 2005 to 2014. Br J Ophthalmol. 2018 Jun 20.
We have read with great interest the e-letter from Karakucuk et al. published in BJO responding to our paper titled ‘Acute retinal toxicity associated with a mixture of perfluorooctane and perfluorohexyloctane: Failure of another indirect cytotoxicity analysis ’ and we appreciate their positive appreciation of our research work.
We consider extraordinarily important that they have reported four more cases in their country, thus, supporting that acute toxicity cases were not a Spanish problem as has been stated by some retinologist at an European congress (Barcelona, September 2017).
We believe that this letter should encourage other colleagues from other countries from all over the world to report cases that certainly exist, according to non-official information from several companies.
We completely agree that the ISO (the International Organization for Standardization) guidelines to determine the in vitro cytotoxicity of intraocular medical devices should be immediately changed. These guidelines should adopt direct cytotoxicity methods to be performed with finished, sterilized, and ready for release products. The analytical method utilized should include cells or tissues close to those of the retina to guarantee specific sensitivity and should be scientifically validated.
We support the suggestion of increasing chemical research, because some companies are promoting chemical tests, as a “safety guarantee”, whose scientific validity and their direct...
We have read with great interest the e-letter from Karakucuk et al. published in BJO responding to our paper titled ‘Acute retinal toxicity associated with a mixture of perfluorooctane and perfluorohexyloctane: Failure of another indirect cytotoxicity analysis ’ and we appreciate their positive appreciation of our research work.
We consider extraordinarily important that they have reported four more cases in their country, thus, supporting that acute toxicity cases were not a Spanish problem as has been stated by some retinologist at an European congress (Barcelona, September 2017).
We believe that this letter should encourage other colleagues from other countries from all over the world to report cases that certainly exist, according to non-official information from several companies.
We completely agree that the ISO (the International Organization for Standardization) guidelines to determine the in vitro cytotoxicity of intraocular medical devices should be immediately changed. These guidelines should adopt direct cytotoxicity methods to be performed with finished, sterilized, and ready for release products. The analytical method utilized should include cells or tissues close to those of the retina to guarantee specific sensitivity and should be scientifically validated.
We support the suggestion of increasing chemical research, because some companies are promoting chemical tests, as a “safety guarantee”, whose scientific validity and their direct correlation with biological tests has not yet been established. As you mentioned the presence of variable concentrations of non-fully fluorinate compounds are undesirable, but these compounds have not been related to acute toxic pictures such as those mentioned in our paper, and probably in your patients, although they could be the bases of variable intraocular inflammatory responses, that prevent the use of PFO as a long-term endotamponade agent.
We read with interest the masterly review of the neuro-ophthalmology of Behcet’s disease by Alghamdi et al (1). One small aspect we question. The authors state that in their patients with papilledema: “The diagnosis of CVT was documented in all patients by cerebral angiography and MRI showing partial or total lack of filling of at least one dural sinus and an elevated CSF opening pressure (>25 mm Hg) on lumbar puncture.” We have recently reported 8 BD patients with pseudotumor cerebri who did not have cerebral venous thrombosis (CVT) on MRI or MRV (2). Partial or total lack of filling of one venous sinus does not constitute the pathophysiological basis for intracranial hypertension; either the sagittal sinus must be occluded, or if only one transverse sinus is occluded then the other needs to be stenosed (3). It would be interesting to know what a review of their patient’s images by a neuro-radiologist would reveal.
1: Alghamdi A, Bodaghi B, Comarmond C, Desbois AC, Domont F, Wechsler B, Depaz R, Le Hoang P, Cacoub P, Touitou V, Saadoun D. Neuro-ophthalmological manifestations of Behçet's disease. Br J Ophthalmol. 2018 Apr 26. pii: bjophthalmol-2017-311334. doi: 10.1136/bjophthalmol-2017-311334.
2: Akdal G, Yaman A, Men S, Çelebisoy N, Toydemir HE, Bajin MS, Akman-Demir G. Pseudotumor cerebri syndrome without cerebral venous sinus thrombosis in Behçet's disease. J Neurol Sci. 2017;383:99-100.
3: Halmagyi GM, Ahmed RM, Johnston IH. The Pseudo...
We read with interest the masterly review of the neuro-ophthalmology of Behcet’s disease by Alghamdi et al (1). One small aspect we question. The authors state that in their patients with papilledema: “The diagnosis of CVT was documented in all patients by cerebral angiography and MRI showing partial or total lack of filling of at least one dural sinus and an elevated CSF opening pressure (>25 mm Hg) on lumbar puncture.” We have recently reported 8 BD patients with pseudotumor cerebri who did not have cerebral venous thrombosis (CVT) on MRI or MRV (2). Partial or total lack of filling of one venous sinus does not constitute the pathophysiological basis for intracranial hypertension; either the sagittal sinus must be occluded, or if only one transverse sinus is occluded then the other needs to be stenosed (3). It would be interesting to know what a review of their patient’s images by a neuro-radiologist would reveal.
1: Alghamdi A, Bodaghi B, Comarmond C, Desbois AC, Domont F, Wechsler B, Depaz R, Le Hoang P, Cacoub P, Touitou V, Saadoun D. Neuro-ophthalmological manifestations of Behçet's disease. Br J Ophthalmol. 2018 Apr 26. pii: bjophthalmol-2017-311334. doi: 10.1136/bjophthalmol-2017-311334.
2: Akdal G, Yaman A, Men S, Çelebisoy N, Toydemir HE, Bajin MS, Akman-Demir G. Pseudotumor cerebri syndrome without cerebral venous sinus thrombosis in Behçet's disease. J Neurol Sci. 2017;383:99-100.
3: Halmagyi GM, Ahmed RM, Johnston IH. The Pseudotumor Cerebri Syndrome: A Unifying Pathophysiological Concept for Patients with Isolated Intracranial Hypertension with Neither Mass Lesion Nor Ventriculomegaly. Neuroophthalmology. 2014;38:249-253.
We read the article ‘Acute retinal toxicity associated with a mixture of perfluorooctane and perfluorohexyloctane: Failure of another indirect cytotoxicity analysis ’ by Coco et al. with great interest.[1] In this study, the authors reported on ocular toxicity due to perfluorooctane (PFO). They advised that the protocols used to determine the cytotoxicity of intraocular medical devices (which have been approved by the Organisation for the Standardisation of International Standards based on indirect methods) should be revised to ensure safety. We congratulate Coco et al.1 for their report because we believe that it has the potential to be a significant contribut or to the literature on this topic.
As is commonly known, PFO is saturated with PFO liquids, which have highly stable carbon-fluorine bonds that consequently make them inert. PFO has highly specific gravity, low viscosity, optical clarity immiscibility in water and interface tension towards water. It is regularly used in vitreoretinal surgery for complex retinal detachment repair because it displaces subretinal fluid and blood anteriorly, unfolds the retina in giant retinal tear cases and provides counter traction and retinal stabilisation during membrane peeling in eyes with proliferative vitreoretinopathy.[2,3] These properties make PFO useful for intraocular surgery. However, some limitations exist regarding PFO use as a long- term tamponade such as amaurosis, a lack of light perce...
We read the article ‘Acute retinal toxicity associated with a mixture of perfluorooctane and perfluorohexyloctane: Failure of another indirect cytotoxicity analysis ’ by Coco et al. with great interest.[1] In this study, the authors reported on ocular toxicity due to perfluorooctane (PFO). They advised that the protocols used to determine the cytotoxicity of intraocular medical devices (which have been approved by the Organisation for the Standardisation of International Standards based on indirect methods) should be revised to ensure safety. We congratulate Coco et al.1 for their report because we believe that it has the potential to be a significant contribut or to the literature on this topic.
As is commonly known, PFO is saturated with PFO liquids, which have highly stable carbon-fluorine bonds that consequently make them inert. PFO has highly specific gravity, low viscosity, optical clarity immiscibility in water and interface tension towards water. It is regularly used in vitreoretinal surgery for complex retinal detachment repair because it displaces subretinal fluid and blood anteriorly, unfolds the retina in giant retinal tear cases and provides counter traction and retinal stabilisation during membrane peeling in eyes with proliferative vitreoretinopathy.[2,3] These properties make PFO useful for intraocular surgery. However, some limitations exist regarding PFO use as a long- term tamponade such as amaurosis, a lack of light perception, optic nerve atrophy, acute retinal necrosis and retinal vascular occlusion (both arterial and/or venous) with disseminated haemorrhages.
Notably, there are controversial results regarding PFO toxicity in the literature. [3-9] The present study was one of the few reports to discuss ocular toxicity due to PFO in the last few years.
Using the current study by Coco et al.1 as a foundation, we would like to share our findings regarding the ocular toxicity of PFO. In our clinic, four patients underwent uneventful vitreoretinal surgery with PFO on the same day by two experienced surgeons (BB, SG). Each patient presented with vitritis, hypopyon and acute retinal toxicity, with no increases seen in either postoperative increased intraocular pressure or pain. Figure 1 (https://i.hizliresim.com/6NQWR0.jpg) shows macular atrophy due to PFO toxicity.
Ocular toxicity may be either mechanical or chemical due to inhibition of and/or changes to tissue functionality and/or rearrangement of tissue parts and inflammatory reactions and/or immune reactions that result in function loss. In the past, intraocular injections of aminoglycoside caused occlusive vascular changes, which were attributed to the pH of the antibiotic.[10] The mechanism of PFO ocular toxicity may be similar. In addition, concentration and contact time may lead to toxicity. For instance, in 2013, some cases of acute blindness due to PFO were reported by Chile’s Health Authorities, while four cases were reported in Spain to the Agency of Medicines and Medical Devices. The problems were attributed to careless manipulation of the Turkish product ; variable concentrations of perfluorodecalin were found in the octane, after which the product was withdrawn.
Unfortunately, scientific reports have yet to clarify the causes of acute blindness. These results may help clinicians choose a short-term ocular tamponade when performing a vitrectomy. In addition, when faced with severe early postoperative intraocular inflammation, such as either vitritis or hypopyon, they should use PFO with care due to the possibility of toxicity and consider early systemic steroid treatment.
In conclusion, more chemical research is needed to clarify the acute ocular toxicity of PFO to ensure the safety of human patients. Additionally, immediate updates to both the European and Organisation for the Standardisation of International Standards guidelines for the biological evaluation of ophthalmic devices are needed.
REFERENCES
1. Coco RM, Srivastava GK, Andrés-Iglesias C, et al. Acute retinal toxicity associated with a mixture of perfluorooctane and perfluorohexyloctane: Failure of another indirect cytotoxicity analysis British Journal of Ophthalmology Published Online First: 29 March 2018. doi: 10.1136/bjophthalmol-2017-311471.
2. Loewenstein A, Humayun MS, de Juan E Jr, et al. Perfluoroperhydrophenanthrene versus perfluoro-n-octane in vitreoretinal surgery. Ophthalmology. 2000;107:1078–1082.
3. Abboud EB, Al-Falah M. Nine Years of Retained Perfluoro-n-octane in the Anterior Chamber after Retinal Detachment Repair with No Signs of Ocular Toxicity. Middle East African Journal of Ophthalmology. 2014;21(3):279-282. doi:10.4103/0974-9233.134697.
4. Stefano Zenoni, Mario R Romano, Sonia Palmieri, Natalia Comi, Edoardo Fiorentini, Piero Fontana. Ocular tolerance and efficacy of short-term tamponade with double filling of polydimethyloxane and perfluoro-n-octane. Clinical Ophthalmology 2011:5 443–449.
5. Zeana D, Becker J, Kuckelkorn R, Kirchhof B. Perfluorohexyloctane as a long-term vitreous tamponade in the experimental animal. Experimental perfluorohexyloctane substitution. Int Ophthalmol. 1999;23(1):17-24.
6. Chang S, Sparrow JR, Iwamoto T, Gershbein A, Ross R, Ortiz R. Experimental studies of tolerance to intravitreal perfluoro-n-octane liquid. Retina. 1991;11(4):367-74. PMID: 1813951.
7. Alharbi SS, Asiri MS. Reversible Corneal Toxicity of Retained Intracameral Perfluoro-n-octane. Middle East African Journal of Ophthalmology. 2016;23(3):277-279. doi:10.4103/0974-9233.186160.
8. Pastor JC, Coco RM, Fernandez-Bueno I, Alonso-Alonso ML, Medina J, Sanz-Arranz A, Rull F, Gayoso MJ, Dueñas A, Garcia-Gutierrez MT, Gonzalez-Buendia L, Delgado-Tirado S, Abecia E, Ruiz-Miguel M, Serrano MA, Ruiz-Moreno JM, Srivastava GK. Acute retinal damage after using a toxic perfuoro-octane for vitreo-retinal surgery. Retina. 2017 Jun;37(6):1140-1151. doi: 10.1097/IAE.0000000000001680.
9. Pradeep S, Chhablani JK, Patel B, Rani P. Delayed inflammation associated with retained perfluorocarbon liquid. Indian J Ophthalmol. 2011 Sep-Oct;59(5):396-8. doi: 10.4103/0301-4738.83623. PMID: 21836352.
10. Waltz K, Margo CE. Intraocular gentamicin toxicity. Arch Ophthalmol 1991;109:911.
Figure Legends:
Figure 1: A 34-year-old man with a macula on a bullous retinal detachment of his right eye. His preoperative visual acuity was 16/20. He was operated on with a 23-G pars plana vitrectomy plus SF6 and a laser. One week after surgery, he complained of very low visual acuity, and he had vitritis, hypopyon and acute retinal toxicity. The patient treated with intravenous methylprednisolone ( 1 mg/kg) and topical prednisolone, moxifloxacin, nepafenac eyedrops four times a day during 4 weeks. One month after surgery, profound atrophy of all layers of the retina were seen on optical coherence tomography. His final visual acuity was counting fingers.
I read with great interest the article by Bae and collegues.1 In their retrospective study, the authors concluded that the presence of atypical epiretinal tissue (AET) in a full-thickness macular hole (FTMH) was related to poorer anatomical success and less visual recovery after surgery.
I agree with the authors on the association of their OCT findings with the visual prognosis. I also agree with them that it is important to identify a good indicator of visual prognosis based on OCT findings. However, there are many confounders to be addressed in this study. For example, preoperative MH size with OCT has been known as a prognostic factor for postoperative visual outcome and anatomical success rate of MH surgery.2,3 A previous study also demonstrated that ERM prevalence increased with severity and size of the FTMH.4 In addition, preoperative visual acuity or preoperative photoreceptor integrity also seems to correlate with visual prognosis.
Thus, their results should be supported by appropriate statistical analysis, that is, multivariate regression analyses. I hope that the authors will comment on the results of multivariate regression analyses to identify the most significant factor to predict visual prognosis after MH surgery.
References
1. Bae K, Lee SM, Kang SW, et al. Atypical epiretinal tissue in full-thickness macular holes: pathogenic and prognostic significance. Br J Ophthalmol. 2018 (in press)
2. Ullrich S, Haritoglou C, Gass...
I read with great interest the article by Bae and collegues.1 In their retrospective study, the authors concluded that the presence of atypical epiretinal tissue (AET) in a full-thickness macular hole (FTMH) was related to poorer anatomical success and less visual recovery after surgery.
I agree with the authors on the association of their OCT findings with the visual prognosis. I also agree with them that it is important to identify a good indicator of visual prognosis based on OCT findings. However, there are many confounders to be addressed in this study. For example, preoperative MH size with OCT has been known as a prognostic factor for postoperative visual outcome and anatomical success rate of MH surgery.2,3 A previous study also demonstrated that ERM prevalence increased with severity and size of the FTMH.4 In addition, preoperative visual acuity or preoperative photoreceptor integrity also seems to correlate with visual prognosis.
Thus, their results should be supported by appropriate statistical analysis, that is, multivariate regression analyses. I hope that the authors will comment on the results of multivariate regression analyses to identify the most significant factor to predict visual prognosis after MH surgery.
References
1. Bae K, Lee SM, Kang SW, et al. Atypical epiretinal tissue in full-thickness macular holes: pathogenic and prognostic significance. Br J Ophthalmol. 2018 (in press)
2. Ullrich S, Haritoglou C, Gass C, et al. Macular hole size as a prognostic factor in macular hole surgery. Br J Ophthalmol 2002;86:390-3.
3. Duker JS, Kaiser PK, Binder S, et al. The International Vitreomacular Traction Study Group classification of vitreomacular adhesion, traction, and macular hole. Ophthalmology 2013;120:2611-9.
4. Cheng L, Freeman WR, Ozerdem U, et al. Prevalence, correlates, and natural history of epiretinal membranes surrounding idiopathic macular holes. Vitrectomy for Macular Hole Study Group. Ophthalmology 2000;107:853-9.
Dear Editor,
We read with interest the paper by Gaier et al.1 The collection of 5 eyes affected by acute A-AION and analyzed with OCT-A is remarkable, due to the rare disease presentation. The main finding of the paper was that during the acute phase of A-AION, diffusely dilated superficial peripapillary capillaries were detectable on OCT-A. Interestingly, peripapillary capillary dilatation was also noted in the fellow eye. Unfortunately, the figures presented by the authors are too small to allow the reader to qualitatively appreciate the capillaries dilatation. More detailed images and a quantitative vessels analysis would have helped to document the microvascular changes.
They hypothesized that the capillary dilatation may represent a form of luxury perfusion in the setting of short ciliary arterial compromise or a centrally mediated autoregolatory mechanisms in the setting of reduced perfusion of the optic nerve. These hypotheses are interesting, but it is important to differentiate the RNFL thickness increase from the capillary dilatation, as peripapillary capillary plexus density and RNFL thickness are highly correlated and fit well with a nonlinear stacked-layer model.2
Moreover, the authors stated that OCT-A laminar analysis did not highlight the choroidal/choriocapillaris perfusion defects seen on FA. However, a recent study3 showed a tight correspondence between the choroidal perfusion defects visible on FA (and even better on indocyanine green...
Dear Editor,
We read with interest the paper by Gaier et al.1 The collection of 5 eyes affected by acute A-AION and analyzed with OCT-A is remarkable, due to the rare disease presentation. The main finding of the paper was that during the acute phase of A-AION, diffusely dilated superficial peripapillary capillaries were detectable on OCT-A. Interestingly, peripapillary capillary dilatation was also noted in the fellow eye. Unfortunately, the figures presented by the authors are too small to allow the reader to qualitatively appreciate the capillaries dilatation. More detailed images and a quantitative vessels analysis would have helped to document the microvascular changes.
They hypothesized that the capillary dilatation may represent a form of luxury perfusion in the setting of short ciliary arterial compromise or a centrally mediated autoregolatory mechanisms in the setting of reduced perfusion of the optic nerve. These hypotheses are interesting, but it is important to differentiate the RNFL thickness increase from the capillary dilatation, as peripapillary capillary plexus density and RNFL thickness are highly correlated and fit well with a nonlinear stacked-layer model.2
Moreover, the authors stated that OCT-A laminar analysis did not highlight the choroidal/choriocapillaris perfusion defects seen on FA. However, a recent study3 showed a tight correspondence between the choroidal perfusion defects visible on FA (and even better on indocyanine green angiography) and on OCT-A at the level of the choriocapillary in a single case of acute A-AION.
The choroidal defects noted on FA by Gaier et al.1 were slightly distant from optic disc border and they did not fit inside the small scan area of the OCT-A exam. Larger OCT-A scan size could help to highlight choriocapillaris perfusion defect in those cases.
References
1 Gaier ED, Gilbert AL, Cestari DM, Miller JB. Optical coherence tomography angiography identifies peripapillary microvascular dilation and focal non-perfusion in giant cell arteritis. Br J Ophthalmol Published Online First: [2017 Nov 9] DOI: 10.1136/bjophthalmol-2017-310718
2 Jia Y, Simonett JM, Wang J1, et al. Wide-Field OCT Angiography Investigation of the Relationship Between Radial Peripapillary Capillary Plexus Density and Nerve Fiber Layer Thickness. Invest Ophthalmol Vis Sci. 2017;58:5188-5194.
3Balducci N, Morara M, Veronese C, et al. Optical coherence tomography angiography in acute arteritic and non-arteritic anterior ischemic optic neuropathy. Graefes Arch Clin Exp Ophthalmol 2017;255:2255-2261.
I was most interested to read the review by Nazarali and co-authors to mark the centenary of the description of the exfoliation syndrome, XFS(1) sometimes called the pseudo-exfoliation syndrome (2). It is always interesting to see how our understanding increases incrementally with time and reviews such as these are important in helping shape further investigations.
The linkage of environmental factors and XFS is important and as they say not well understood. Nazarali and co-authors might like to reflect on the findings in Australian Aboriginal people (3). Aboriginal people were found to have very high rates of XFS, being present in 16% of those aged 60 and above. The presence of XFS was related to total global radiation exposure and occupation. Most interestingly, XFS was not associated with high intraocular pressure or glaucoma. Surely this is an area where more research is required.
1. Nazarali S, Damji F, Damji KF. What have we learned about exfoliation syndrome since its discovery by John Lindberg 100 years ago? Br J Ophthalmol 2018; doi:10.1136/bjophthalmol-2017-3111321
2.Dvorak-Theobald G. Pseudo-exfoliation of the lens capsule - relation to “true” exfoliation of the lens capsule as reported in the literature and role in the production of glaucoma capsulocuticulare. Am J Ophthalmol 2018; doi.org/10.1016/j.ajo2108.02.018
3. Taylor HR. Pseudoexfoliation, an environmental disease? Trans Ophthalmol Socs UK 1979; 99: 302-307...
I was most interested to read the review by Nazarali and co-authors to mark the centenary of the description of the exfoliation syndrome, XFS(1) sometimes called the pseudo-exfoliation syndrome (2). It is always interesting to see how our understanding increases incrementally with time and reviews such as these are important in helping shape further investigations.
The linkage of environmental factors and XFS is important and as they say not well understood. Nazarali and co-authors might like to reflect on the findings in Australian Aboriginal people (3). Aboriginal people were found to have very high rates of XFS, being present in 16% of those aged 60 and above. The presence of XFS was related to total global radiation exposure and occupation. Most interestingly, XFS was not associated with high intraocular pressure or glaucoma. Surely this is an area where more research is required.
1. Nazarali S, Damji F, Damji KF. What have we learned about exfoliation syndrome since its discovery by John Lindberg 100 years ago? Br J Ophthalmol 2018; doi:10.1136/bjophthalmol-2017-3111321
2.Dvorak-Theobald G. Pseudo-exfoliation of the lens capsule - relation to “true” exfoliation of the lens capsule as reported in the literature and role in the production of glaucoma capsulocuticulare. Am J Ophthalmol 2018; doi.org/10.1016/j.ajo2108.02.018
3. Taylor HR. Pseudoexfoliation, an environmental disease? Trans Ophthalmol Socs UK 1979; 99: 302-307
We were interested to see Roberts, et. al study [1] which explored whether a hub-and-spoke model using a femtosecond laser (FL) could increase the efficiency and reduce the cost of cataract surgery.
Although the model was not cost-effective when compared to conventional phacoemulsification surgery, more efficient models should continue to be assessed. The Aravind Eye Care system uses an alternative hub-and-spoke model. Instead of separate operating theatres (OTs), the physician alternates between two beds in a single OT. This model, and the safe reuse of surgical supplies, results in phacoemulsification cataract surgery with excellent outcomes at 1/20th the cost and carbon emissions [2-4].
Roberts, et. al recommend that the ideal number of OTs to maximise the utility of an FL in a hub-and-spoke model is four. However, they were not able to evaluate the effect of adding additional OTs to their model as they only had two OTs. We suggest that adopting the Aravind model to jump to the 1:4 model without further building work could significantly alter this paper’s conclusions. We would be interested to know if elements of the Aravind model, two beds one theatre, could be adopted in their setting.
On average patients receiving FLACS spent 5.85±1.99 mins in the laser suite (LS), implying a potential throughput of between 8 and 15 cases per hour. We are interested to know the authors views on the the limits of the FL and what impact the adoption of bilateral...
We were interested to see Roberts, et. al study [1] which explored whether a hub-and-spoke model using a femtosecond laser (FL) could increase the efficiency and reduce the cost of cataract surgery.
Although the model was not cost-effective when compared to conventional phacoemulsification surgery, more efficient models should continue to be assessed. The Aravind Eye Care system uses an alternative hub-and-spoke model. Instead of separate operating theatres (OTs), the physician alternates between two beds in a single OT. This model, and the safe reuse of surgical supplies, results in phacoemulsification cataract surgery with excellent outcomes at 1/20th the cost and carbon emissions [2-4].
Roberts, et. al recommend that the ideal number of OTs to maximise the utility of an FL in a hub-and-spoke model is four. However, they were not able to evaluate the effect of adding additional OTs to their model as they only had two OTs. We suggest that adopting the Aravind model to jump to the 1:4 model without further building work could significantly alter this paper’s conclusions. We would be interested to know if elements of the Aravind model, two beds one theatre, could be adopted in their setting.
On average patients receiving FLACS spent 5.85±1.99 mins in the laser suite (LS), implying a potential throughput of between 8 and 15 cases per hour. We are interested to know the authors views on the the limits of the FL and what impact the adoption of bilateral sequential cataract surgery might have on their cost estimates, [5] assumptions about throughput and the potential viability of more intensive 1:6 or 1:8 models.
Finally, maintaining training standards while improving efficiency is a challenge and we would be interested in the authors views on how training is best catered for within their different hub and spoke models.
References
1. Roberts HW, Wagh VK, Mullens IJM, Borsci S, Ni MZ, O’Brart DPS. Evaluation of a hub-and-spoke model for the delivery of femtosecond laser-assisted cataract surgery within the context of a large randomised controlled trial. Br. J. Ophthalmol. 2018 doi: 10.1136/bjophthalmol-2017-311319
2. Thiel CL, Schehlein E, Ravilla T, et al. Cataract surgery and environmental sustainability: Waste and lifecycle assessment of phacoemulsification at a private healthcare facility. J. Cataract Refract. Surg. 2017;43(11):1391-98 doi: https://doi.org/10.1016/j.jcrs.2017.08.017
3. Hong-Gam Le JRE, Rengaraj Venkatesh, Aravind Srinivasan, Ajay Kolli, Aravind Haripriya, R. D. Ravindran, Thulasiraj Ravilla, Alan L. Robin, David W. Hutton, Joshua D. Stein. A Sustainable Model For Delivering High-Quality Efficient Cataract Surgery In Southern India. Health Aff. (Millwood). 2016;35(10):1783-90
4. Venkatesh R, van Landingham SW, Khodifad AM, et al. Carbon footprint and cost–effectiveness of cataract surgery. Curr. Opin. Ophthalmol. 2016;27(1):82-88
5. Grzybowski A, Wasinska-Borowiec W, Claoué C. Pros and cons of immediately sequential bilateral cataract surgery (ISBCS). Saudi Journal of Ophthalmology 2016;30(4):244-49 doi: 10.1016/j.sjopt.2016.09.001
Dear Editor,
Show MoreWe thank Dr. Balducci and her colleagues for their interest in our paper [1]. They raise several important points regarding optic nerve angiography, and we are thankful to have the opportunity to discuss these items further.
In preparation of our manuscript, we felt that diffuse changes in the peripapillary capillary network were best appreciated at lower magnification. Balancing this objective in presentation with a sufficient resolution to appreciate the focal deficits we highlighted, the image sizes published represent what we felt was the best compromise. For those who feel that higher magnification images are needed, we have included in this letter Figure 1, which includes the same 6x6 mm OCT-A images in the acute phase for all cases in our study. Quantitation of OCT-A signal can be a powerful way to objectively assess regional as well as between eye and patient differences. We have recently performed a quantitative assessment of angiographic signal in non-arteritic anterior ischemic optic neuropathy using a different device, the Optovue Avanti (Fremont, CA) [1]. However, in the current study, the small number of affected eyes did not allow for meaningful statistical analysis of quantitative data. In addition, quantitative analyses can be misleading when confounding artifacts or segmentation errors are present as discussed below.
Jia and colleagues [2] showed a strong non-linear correlation between RNFL thickness and radial peripapillary...
Dear Sir,
We appreciate Dr. Taylor’s interest in our paper as well as drawing our attention to environmental factors that may influence XFS in Australian aboriginal people. Certainly, this is an area that deserves further investigation. Dr Taylor’s review article presents some interesting findings, particularly regarding the high incidence of XFS in Aboriginal individuals. (1)
Consistent with recent literature, Dr. Taylor identified a ‘latitude effect’. Interestingly however, XFS was more commonly observed at lower latitudes, which contrasts other findings of high altitude exposure associated with XFS in an American population. (2)
The recognition of solar radiation exposure as an environmental factor associated with XFS is plausible due to accumulating evidence that supports this relationship. (3) While providing some useful insights, this article justifies the lack of understanding and the need for further research on environmental factors.
1. Taylor HR. Pseudoexfoliation, an environmental disease? Trans Ophthalmol Socs UK 1979; 99: 302- 307
...Show More2. Stein JD, Pasquale LR, Talwar N, Kim DS, Reed DM, Nan B, Kang JH, Wiggs JL,Richards JE. Geographic and climatic factors associated with exfoliation syndrome. Arch Ophthalmol. 2011 Aug;129(8):1053-60.
3. Jiwani AZ, Pasquale LR. Exfoliation Syndrome and Solar Exposure: New Epidemiological Insights Into the Pathophysiology of the Disease. International ophthalmology clinics. 2015;55(4):13.
Dear Editor,
We read with interest the article written by Creuzot-Garcher and colleagues that was published in the June 2018 issue of your journal. 1 The authors retrospectively reviewed billings codes from a national database in France from January 2004 to December 2014 to examine acute postoperative endophthalmitis (POE) rates. They reported an incidence of acute POE in stand-alone phacoemulsification of 0.102% over this 11-year period. In contrast, combined surgery in which phacoemulsification was performed with another intraocular procedure had an overall higher incidence of 0.149%. The incidence of acute POE in combined phacoemulsification and glaucoma surgery, corneal surgery, and vitreoretinal surgery was found to be 0.089%, 0.142%, and 0.223% respectively.
As Creuzot-Garcher and colleagues mention, many phakic patients who undergo either glaucoma surgery, corneal surgery, or vitreoretinal surgery, are elderly and likely will require cataract extraction at some point.1 In addition, it is well established that these surgeries promote cataract formation in phakic eyes, and therefore patients who do not undergo combination surgery will likely require stand-alone cataract surgery in the future.
Hence, it would be instructive to compare the risk of acute POE in combined surgery with the total risk conferred by separately performing the two surgeries. We made the assumption that the chance of endophthalmitis in each surgery is independent. Using the...
Show MoreWe have read with great interest the e-letter from Karakucuk et al. published in BJO responding to our paper titled ‘Acute retinal toxicity associated with a mixture of perfluorooctane and perfluorohexyloctane: Failure of another indirect cytotoxicity analysis ’ and we appreciate their positive appreciation of our research work.
Show MoreWe consider extraordinarily important that they have reported four more cases in their country, thus, supporting that acute toxicity cases were not a Spanish problem as has been stated by some retinologist at an European congress (Barcelona, September 2017).
We believe that this letter should encourage other colleagues from other countries from all over the world to report cases that certainly exist, according to non-official information from several companies.
We completely agree that the ISO (the International Organization for Standardization) guidelines to determine the in vitro cytotoxicity of intraocular medical devices should be immediately changed. These guidelines should adopt direct cytotoxicity methods to be performed with finished, sterilized, and ready for release products. The analytical method utilized should include cells or tissues close to those of the retina to guarantee specific sensitivity and should be scientifically validated.
We support the suggestion of increasing chemical research, because some companies are promoting chemical tests, as a “safety guarantee”, whose scientific validity and their direct...
We read with interest the masterly review of the neuro-ophthalmology of Behcet’s disease by Alghamdi et al (1). One small aspect we question. The authors state that in their patients with papilledema: “The diagnosis of CVT was documented in all patients by cerebral angiography and MRI showing partial or total lack of filling of at least one dural sinus and an elevated CSF opening pressure (>25 mm Hg) on lumbar puncture.” We have recently reported 8 BD patients with pseudotumor cerebri who did not have cerebral venous thrombosis (CVT) on MRI or MRV (2). Partial or total lack of filling of one venous sinus does not constitute the pathophysiological basis for intracranial hypertension; either the sagittal sinus must be occluded, or if only one transverse sinus is occluded then the other needs to be stenosed (3). It would be interesting to know what a review of their patient’s images by a neuro-radiologist would reveal.
1: Alghamdi A, Bodaghi B, Comarmond C, Desbois AC, Domont F, Wechsler B, Depaz R, Le Hoang P, Cacoub P, Touitou V, Saadoun D. Neuro-ophthalmological manifestations of Behçet's disease. Br J Ophthalmol. 2018 Apr 26. pii: bjophthalmol-2017-311334. doi: 10.1136/bjophthalmol-2017-311334.
Show More2: Akdal G, Yaman A, Men S, Çelebisoy N, Toydemir HE, Bajin MS, Akman-Demir G. Pseudotumor cerebri syndrome without cerebral venous sinus thrombosis in Behçet's disease. J Neurol Sci. 2017;383:99-100.
3: Halmagyi GM, Ahmed RM, Johnston IH. The Pseudo...
Dear Editor:
We read the article ‘Acute retinal toxicity associated with a mixture of perfluorooctane and perfluorohexyloctane: Failure of another indirect cytotoxicity analysis ’ by Coco et al. with great interest.[1] In this study, the authors reported on ocular toxicity due to perfluorooctane (PFO). They advised that the protocols used to determine the cytotoxicity of intraocular medical devices (which have been approved by the Organisation for the Standardisation of International Standards based on indirect methods) should be revised to ensure safety. We congratulate Coco et al.1 for their report because we believe that it has the potential to be a significant contribut or to the literature on this topic.
As is commonly known, PFO is saturated with PFO liquids, which have highly stable carbon-fluorine bonds that consequently make them inert. PFO has highly specific gravity, low viscosity, optical clarity immiscibility in water and interface tension towards water. It is regularly used in vitreoretinal surgery for complex retinal detachment repair because it displaces subretinal fluid and blood anteriorly, unfolds the retina in giant retinal tear cases and provides counter traction and retinal stabilisation during membrane peeling in eyes with proliferative vitreoretinopathy.[2,3] These properties make PFO useful for intraocular surgery. However, some limitations exist regarding PFO use as a long- term tamponade such as amaurosis, a lack of light perce...
Show MoreI read with great interest the article by Bae and collegues.1 In their retrospective study, the authors concluded that the presence of atypical epiretinal tissue (AET) in a full-thickness macular hole (FTMH) was related to poorer anatomical success and less visual recovery after surgery.
I agree with the authors on the association of their OCT findings with the visual prognosis. I also agree with them that it is important to identify a good indicator of visual prognosis based on OCT findings. However, there are many confounders to be addressed in this study. For example, preoperative MH size with OCT has been known as a prognostic factor for postoperative visual outcome and anatomical success rate of MH surgery.2,3 A previous study also demonstrated that ERM prevalence increased with severity and size of the FTMH.4 In addition, preoperative visual acuity or preoperative photoreceptor integrity also seems to correlate with visual prognosis.
Thus, their results should be supported by appropriate statistical analysis, that is, multivariate regression analyses. I hope that the authors will comment on the results of multivariate regression analyses to identify the most significant factor to predict visual prognosis after MH surgery.
References
Show More1. Bae K, Lee SM, Kang SW, et al. Atypical epiretinal tissue in full-thickness macular holes: pathogenic and prognostic significance. Br J Ophthalmol. 2018 (in press)
2. Ullrich S, Haritoglou C, Gass...
Dear Editor,
Show MoreWe read with interest the paper by Gaier et al.1 The collection of 5 eyes affected by acute A-AION and analyzed with OCT-A is remarkable, due to the rare disease presentation. The main finding of the paper was that during the acute phase of A-AION, diffusely dilated superficial peripapillary capillaries were detectable on OCT-A. Interestingly, peripapillary capillary dilatation was also noted in the fellow eye. Unfortunately, the figures presented by the authors are too small to allow the reader to qualitatively appreciate the capillaries dilatation. More detailed images and a quantitative vessels analysis would have helped to document the microvascular changes.
They hypothesized that the capillary dilatation may represent a form of luxury perfusion in the setting of short ciliary arterial compromise or a centrally mediated autoregolatory mechanisms in the setting of reduced perfusion of the optic nerve. These hypotheses are interesting, but it is important to differentiate the RNFL thickness increase from the capillary dilatation, as peripapillary capillary plexus density and RNFL thickness are highly correlated and fit well with a nonlinear stacked-layer model.2
Moreover, the authors stated that OCT-A laminar analysis did not highlight the choroidal/choriocapillaris perfusion defects seen on FA. However, a recent study3 showed a tight correspondence between the choroidal perfusion defects visible on FA (and even better on indocyanine green...
Dear Sir,
I was most interested to read the review by Nazarali and co-authors to mark the centenary of the description of the exfoliation syndrome, XFS(1) sometimes called the pseudo-exfoliation syndrome (2). It is always interesting to see how our understanding increases incrementally with time and reviews such as these are important in helping shape further investigations.
The linkage of environmental factors and XFS is important and as they say not well understood. Nazarali and co-authors might like to reflect on the findings in Australian Aboriginal people (3). Aboriginal people were found to have very high rates of XFS, being present in 16% of those aged 60 and above. The presence of XFS was related to total global radiation exposure and occupation. Most interestingly, XFS was not associated with high intraocular pressure or glaucoma. Surely this is an area where more research is required.
1. Nazarali S, Damji F, Damji KF. What have we learned about exfoliation syndrome since its discovery by John Lindberg 100 years ago? Br J Ophthalmol 2018; doi:10.1136/bjophthalmol-2017-3111321
Show More2.Dvorak-Theobald G. Pseudo-exfoliation of the lens capsule - relation to “true” exfoliation of the lens capsule as reported in the literature and role in the production of glaucoma capsulocuticulare. Am J Ophthalmol 2018; doi.org/10.1016/j.ajo2108.02.018
3. Taylor HR. Pseudoexfoliation, an environmental disease? Trans Ophthalmol Socs UK 1979; 99: 302-307...
We were interested to see Roberts, et. al study [1] which explored whether a hub-and-spoke model using a femtosecond laser (FL) could increase the efficiency and reduce the cost of cataract surgery.
Although the model was not cost-effective when compared to conventional phacoemulsification surgery, more efficient models should continue to be assessed. The Aravind Eye Care system uses an alternative hub-and-spoke model. Instead of separate operating theatres (OTs), the physician alternates between two beds in a single OT. This model, and the safe reuse of surgical supplies, results in phacoemulsification cataract surgery with excellent outcomes at 1/20th the cost and carbon emissions [2-4].
Roberts, et. al recommend that the ideal number of OTs to maximise the utility of an FL in a hub-and-spoke model is four. However, they were not able to evaluate the effect of adding additional OTs to their model as they only had two OTs. We suggest that adopting the Aravind model to jump to the 1:4 model without further building work could significantly alter this paper’s conclusions. We would be interested to know if elements of the Aravind model, two beds one theatre, could be adopted in their setting.
On average patients receiving FLACS spent 5.85±1.99 mins in the laser suite (LS), implying a potential throughput of between 8 and 15 cases per hour. We are interested to know the authors views on the the limits of the FL and what impact the adoption of bilateral...
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