We thank the authors[1] but wish to clarify several points. Stating that ‘glaucoma diagnosis is more common in OSA populations’ is controversial. Glaucoma diagnosis was not more common in our study (RR 1.01, CI 0.85-1.19), which censored prospectively from time of OSA coding throughout England from 1999-2011[2]. This is the largest and longest individual study conducted in this area. Several previous studies also observed no association.
The authors recommend accounting for ‘risk-associated conditions’. Accounting for potential confounders is important in evaluation of positive associations but less relevant in their absence. We agree that studies in different populations would be useful, particularly in Asia where OAG may differ.
In recommending a prospective RCT assessing ‘IOP/visual field progression before and after CPAP’, the authors are asking a different question. We have previously advocated this: ‘even in the absence of a positive association, it might still be relevant to identify those patients with genuine co-existence of OSA and POAG, particularly if evidence were to emerge … that OSA treatment could reduce glaucomatous progression’[2].
Our study never aimed to measure OSA point prevalence, so it is inappropriate to compare a speculative ‘base rate of 2.5%’ with prevalence estimates from a different continent/age-group. Moreover, our OSA cohort represented more severe disease; this should have exaggerated rather than ‘blurred’ any potentia...
We thank the authors[1] but wish to clarify several points. Stating that ‘glaucoma diagnosis is more common in OSA populations’ is controversial. Glaucoma diagnosis was not more common in our study (RR 1.01, CI 0.85-1.19), which censored prospectively from time of OSA coding throughout England from 1999-2011[2]. This is the largest and longest individual study conducted in this area. Several previous studies also observed no association.
The authors recommend accounting for ‘risk-associated conditions’. Accounting for potential confounders is important in evaluation of positive associations but less relevant in their absence. We agree that studies in different populations would be useful, particularly in Asia where OAG may differ.
In recommending a prospective RCT assessing ‘IOP/visual field progression before and after CPAP’, the authors are asking a different question. We have previously advocated this: ‘even in the absence of a positive association, it might still be relevant to identify those patients with genuine co-existence of OSA and POAG, particularly if evidence were to emerge … that OSA treatment could reduce glaucomatous progression’[2].
Our study never aimed to measure OSA point prevalence, so it is inappropriate to compare a speculative ‘base rate of 2.5%’ with prevalence estimates from a different continent/age-group. Moreover, our OSA cohort represented more severe disease; this should have exaggerated rather than ‘blurred’ any potential association.
The finding of a temporary elevation in OSA rate ratios soon after POAG diagnosis (offset later) is likely explained by increased effort screening for OSA through publicity around this potential association. These findings do not necessarily demonstrate a ‘lack of OSA screening’. Our findings do suggest that OSA screening might be directed towards AMD patients[3,4].
The recommendation of a ‘national OSA screening programme for all’ is a separate matter that should be judged on its own merits in an evidence-based manner.
References
1. Weir RE and Hozer KW. Ophthalmologists wake obstructive sleeping dogma. BJO 2017 eLetter
2. Keenan TD, Goldacre R, Goldacre MJ. Associations between obstructive sleep apnoea, primary open angle glaucoma and age-related macular degeneration: record linkage study. BJO 2017;101(2):155-159.
3. Keenan TD. Correspondence. Retina 2016;36(7):e70-1
4. Schaal S, Sherman MP, Nesmith B, Barak Y. Untreated obstructive sleep apnea hinders response to bevacizumab in age-related macular degeneration. Retina 2016;36(4):791-7
Dear Sirs,
We are grateful to Sabour and Ghassemi for their interest in our recent
article[1]. In our understanding, they query why we did not use intra class
correlation (ICC) as a measure for precision.
Our test-retest reliability (absolute agreement ICC) is derived from the
maximum likelihood (LM) estimates of the one-way random effects model of
the form: yij...
Dear Sirs,
We are grateful to Sabour and Ghassemi for their interest in our recent
article[1]. In our understanding, they query why we did not use intra class
correlation (ICC) as a measure for precision.
Our test-retest reliability (absolute agreement ICC) is derived from the
maximum likelihood (LM) estimates of the one-way random effects model of
the form: yij=Mu+ri+Epsilonij, where yij is the measurement of the ith eye by the jth measurement (say spherical equivalent measured on the first (second or third) occasion), Mu is the mean rating (say mean spherical equivalent), ri is the eye random effect and Epsilonij is a random error. As described in Rabe-Hesketh and Skrondal[2], the reliability is calculated as
p ?=? ?/(? ?+? ?),
where Psi is a between-subject variance and Theta is a within-subject variance.
Here we assume that n eyes are randomly selected from the population of
potential eyes. Each one is measured by a different set of k measurements,
randomly drawn from the population of potential measurements. The
consistency of agreement is not defined in this case, as each eye is
evaluated by a different set of measurements. Thus, there is no between-
measurements variability in this model.
We agree that clinical judgement is paramount, which is why, indeed, we
state in our paper (p 5) that "the clinical interpretation of the
agreement range (...) is vital (underlining added)". It is before the
background of such clinical interpretations in the paper and of the above
explanations that we derived our conclusions in, as we trust, an
appropriate way.
Yours respectfully,
References
1. Huelle JO, Katz T, Druchkiv V, et al. First clinicial results on
the feasibility, quality and reproducibility of aberrometry-based
intraoperative refraction during cataract surgery. Br J Ophthalmol 2014.
2. Rabe-Hesketh S, Skrondal A. Multilevel and Longitudinal Modeling Using
Stata, Second Edition: Stata Press, 2008.
3. McAlinden C, Khadka J, Pesudovs K. Statistical methods for conducting
agreement (comparison of clinical tests) and precision (repeatability or
reproducibility) studies in optometry and ophthalmology. Ophthalmic
Physiol Opt 2011;31(4):330-8.
We were interested to read the approach taken by Sahni and Clark [1]
to facilitate the effective Argon laser treatment of trichiasis. They
have ably reviewed the complications of trichiasis, the different forms of
management of trichiasis, the advantages of Argon laser treatment in the
management of trichiasis, the technique of Argon laser trichiasis therapy,
and the limitations of lash laser the...
We were interested to read the approach taken by Sahni and Clark [1]
to facilitate the effective Argon laser treatment of trichiasis. They
have ably reviewed the complications of trichiasis, the different forms of
management of trichiasis, the advantages of Argon laser treatment in the
management of trichiasis, the technique of Argon laser trichiasis therapy,
and the limitations of lash laser therapy.
We take issue with the authors in two areas. Firstly, the almost certain
consequence of using a duration of laser treatment of 0.1 second is that
if the laser "takes", the lash will disappear within the space of a few
laser shots, effectively precluding the effective destruction of that
particular lash follicle. We have particularly made it a point that when
teaching trainees the technique of lash laser, we ensure that the energy
burst lasts long enough to commence visible lash destruction as well as
destruction of the subcutaneous lash, as the burn is directed towards the
lash follicle. Thus, we always use a duration of several seconds, or even
continuous energy, and aim to achieve initiation of effective lash
destruction above the lid level after the first shot, or certainly within
three shots. Thus, one- to three-second-duration bursts may be required,
depending on the individual lash. Just a few more shots will effectively
and completely destroy the subcutaneous lash and its follicle.
Secondly, the article by Bartley and Lowry quoted by the authors,
describes using a "drop of ink from a fountain pen" to facilitate lash
laser.[2] Presumable in the interests of sterility, Sahni and Clark have
used the ink from a "blue skin marker pen" to allow improved absorption of
Argon laser energy. While using a fresh marker pen for each patient may
be relatively efficient, it could not be regarded as cost effective. By
contrast, in a procedure described by us in 1994,[3] we found that
transferring a tiny drop of the patient's own blood, whether still liquid
or already coagulated, to the lash base on the lid margin is a simple,
rapid, cheap, safe and highly effective method of getting the laser
reaction started when the lashes are pale. We have found that the
required amount of blood is invariably present on the patient's own lid
skin at the site of local anaesthetic infiltration. We usually transfer
it by picking it up with a sterile drawing-up needle. This is achieved
remarkably easily on the laser slit lamp, which allows adequate
magnification for the accurate siting of the transferred blood.
Geoffrey A. Wilcsek
Ian C. Francis
The Ocular Plastics Unit
Prince of Wales Hospital and the University of New South
Wales Randwick Sydney, Australia
References
(1) Sahni J, Clark D. Argon laser and trichiasis: a helpful tip.
Br J Ophthalmol 2001;85:761
(2) Bartley GB, Lowry JC. Argon laser treatment of trichiasis.
Am J Ophthalmol 1992;113:71-4
(3) Ghabrial R, Francis IC, Kappagoda MB. Autologous blood facilitation of
lid laser treatment. Aust NZ J Ophthalmol 1994.
Impact of initial visual acuity on anti-VEGF treatment outcomes in
patients with macular oedema secondary to retinal vein occlusions in
routine clinical practice
Dan Calugaru, Mihai Calugaru
Department of Ophthalmology, Univ of Medicine Cluj-Napoca/Romania
Re: Impact of initial visual acuity on anti-VEGF treatment outcomes in
patients with macular oedema secondary to retinal vein occlusions in
routine clinical practice...
Impact of initial visual acuity on anti-VEGF treatment outcomes in
patients with macular oedema secondary to retinal vein occlusions in
routine clinical practice
Dan Calugaru, Mihai Calugaru
Department of Ophthalmology, Univ of Medicine Cluj-Napoca/Romania
Re: Impact of initial visual acuity on anti-VEGF treatment outcomes in
patients with macular oedema secondary to retinal vein occlusions in
routine clinical practice. Wai et al. Br J Ophthalmol
2016;http:/dx.doi.org/10.1136/bjophthalmol-2016-308727.
Dear Editor
We would like to address several challenges arising from the study by Wai
et al (1), which can be specifically summarized as follows:
1. The study was retrospectively conducted with the existence of a
selection bias because the choise of the specific anti-vascular
endothelial growth factor (VEGF) agent was based on physician and patient
preference. In addition, patients were retreated based on investigator
determination of the presence of subretinal or intraretinal fluid as seen
either by comprehensive ophthalmic examination and/or spectral-domain
optical coherence tomography.
2. The authors stated that there were relatively few numbers of
ischaemic patients in their series although fluorescein angiography was
performed in only 60.45% of the patients and no criteria used for the
classification of patients as having ischaemic retinal vein occlusion
(RVO) were indicated.
3. The authors concluded that RVO patients with better initial visual
acuities (VA) showed a nonsignificant change in VA and central subfield
thickness (CST) over 12 months of treatment; conversely, patients with
poor initial VAs showed dramatic improvements in Early Treatment Diabetic
Retinopathy Study (ETDRS) letters and CST.
4. In 2015, we documented for the first time (2), the impact of
initial VA on bevacizumab (Avastin; Genentech, Inc.,
San Francisco, CA) treatment outcomes in patients with macular oedema
secondary to acute central/hemicentral retinal vein occlusions. Although
VA improvements at month 36 were significant in patients with both
nonischaemic and ischaemic occlusions, the magnitudes of response to
treatment were totally different, namely, an increase in VA of 17.5
letters (from 48.6 to 65.75 letters) in case of nonischaemic forms and of
26.81 letters (from 7.6 to 34.41 letters) in patients with ischaemic
occlusions. The proportions of VA increases (from baseline values) were
36% in patients with better initial VA and 352.7% in patients having a
poor initial VA, respectively. Such a comparison helped us to know that
the intravitreal bevacizumab therapy was more effective in patients with
ischaemic occlusions who required a significantly higher number of
injections. In contrast with VA changes, the magnitudes of CST response to
treatment were different, for example, a decrease of 300.49 microns in
cases of nonischaemic and 351.33 microns in patients of ischaemic
occlusions. However, the proportions of CST reductions (from baseline
values) were similar in the nonischaemic and ischaemic groups (56.62% and
56.54%, respectively). So, the anatomic outcomes did not mirror the visual
results mentioned above.
Altogether, the assumption according to which patients with poor
initial VA may benefit most from anti-VEGF suppression and vice versa,
seems to be a somewhat paradoxical and counter-intuitive finding because
patients with poor initial VA usually have advanced lesions which are
difficult to be recovered. And yet, this assertion is logical since
patients with low initial VA have a larger range of the interval in which
VA can be improved in comparison with patients having a better initial VA
with a more narrow interval and with small possibilities for improving.
References
1. Wai KM, Khan M, Srivastava S, et al. Impact of initial visual acuity on
anti-VEGF treatment outcomes in patients with macular oedema secondary to
retinal vein occlusions in routine clinical practice. Br J Ophthalmol
2016; http:/dx.doi.org/10.1136/bjophthalmol-2016-308727.
2. Calugaru D, Calugaru M. Intravitreal bevacizumab in acute
central/hemicentral retinalvein occlusions: three-year results of a
prospective clinical study. J Ocul Pharmacol Ther 2015;31(2):78-86.
We have read with great interest Yokouchi et al’s article on the correlation between vascular endothelial growth factor (VEGF) levels and peripapillary retinal thickness in patients with POEMS syndrome(1) and we would like to share some reflections onthis mysterious form of optic neuropathy.
The acronym that gives name to the disorder does not include any ocular manifestation. However these patients frequently do develop ocular manifestations. Bilateral optic disc involvement appears in half of the patients and it has been considered an independent prognostic factor.(2)POEMS syndrome associated optic disc swelling constitutes a form of optic neuropathy that is not easy to classify. It is usually bilateral, but intracranial pressure is not elevated in most patients, so the term papilledema (although commonly used) is probably inaccurate. Most authors believe this optic neuropathy is related to increased VEGF levels, and Yokouchi et al’s work seems to support this theory.(1) From a pathogenic point of view optic disc swelling induced by cytokines should probably be considered a form of optic neuritis. However, inflammatory neuropathies often associate pain with eye movements and usually produce visual loss (reduced visual acuity and visual field damage) while POEMS patients present only minor visual disturbance and the visual prognosis is good.(3)
We suggest that POEMS associated optic disc swelling should be considered a new form of optic neuropathy. This neuro...
We have read with great interest Yokouchi et al’s article on the correlation between vascular endothelial growth factor (VEGF) levels and peripapillary retinal thickness in patients with POEMS syndrome(1) and we would like to share some reflections onthis mysterious form of optic neuropathy.
The acronym that gives name to the disorder does not include any ocular manifestation. However these patients frequently do develop ocular manifestations. Bilateral optic disc involvement appears in half of the patients and it has been considered an independent prognostic factor.(2)POEMS syndrome associated optic disc swelling constitutes a form of optic neuropathy that is not easy to classify. It is usually bilateral, but intracranial pressure is not elevated in most patients, so the term papilledema (although commonly used) is probably inaccurate. Most authors believe this optic neuropathy is related to increased VEGF levels, and Yokouchi et al’s work seems to support this theory.(1) From a pathogenic point of view optic disc swelling induced by cytokines should probably be considered a form of optic neuritis. However, inflammatory neuropathies often associate pain with eye movements and usually produce visual loss (reduced visual acuity and visual field damage) while POEMS patients present only minor visual disturbance and the visual prognosis is good.(3)
We suggest that POEMS associated optic disc swelling should be considered a new form of optic neuropathy. This neuropathy is probably due to the toxicity of elevated systemic VEGF and represents another manifestation of the organomegalia which characterizes the disease. We propose “VEGF-induced papillomegalia” as a more accurate term to designate optic nerve involvement in POEMS syndrome.
Reference List
1. Yokouchi H, Baba T, Misawa S, Sawai S, Kitahashi M, Oshitari T, et al. Correlation between peripapillary retinal thickness and serum level of vascular endothelial growth factor in patients with POEMS syndrome. Br J Ophthalmol. 2015.
2. Cui R, Yu S, Huang X, Zhang J, Tian C, Pu C. Papilloedema is an independent prognostic factor for POEMS syndrome. J Neurol. 2014;261(1):60-5.
3. Gonzalez-Martin-Moro J, Contreras I, Pilo-de-la-Fuente B, Gomez-Sanz F. Temporal and Spatial Correlation Between Choroidal Thickness and Visual Function in a Case of POEMS Syndrome. Ocul Immunol Inflamm. 2016:1-4.
We read with great interest the article by Keenan et al. “Associations between obstructive sleep apnoea, primary open angle glaucoma and age-related macular degeneration: record linkage study” (Br J Ophthalmol. 2017 Feb;101(2):155-159), which concluded that Obstructive Sleep Apnoea (OSA) is not associated with Primary Open Angle Glaucoma (POAG). Potential POAG aetiology inflammatory markers are higher in OSA patients, and glaucoma diagnosis is more common in OSA populations.
While retrospective studies have great value, it is important to account for risk-associated conditions, including family history of OSA, racial disparities [1], smoking, hypertension, floppy eyelids, Type II diabetes [2], COPD and obesity.
To determine a causal relationship between OSA and POAG, it is necessary to assess intraocular pressures/visual field progression before and after continuous positive airway pressure (CPAP) treatment, using prospective randomised control trial designs. Further, the OSA base rate in Keenan et al. was 2.5%, while the estimated OSA prevalence rate may exceed 20% for those over 55 years of age [3]. Missing 90+% of apnoea sufferers may have blurred the true apnoea-POAG relationship. The risk rate for apnoea in the first year after initial POAG episode was 1.5, but declined to less than 1.0 in subsequent years, which suggests the possibility of increasing neglect of apnoea risk over the course of POAG. These findings highlight the lack of OSA screening and...
We read with great interest the article by Keenan et al. “Associations between obstructive sleep apnoea, primary open angle glaucoma and age-related macular degeneration: record linkage study” (Br J Ophthalmol. 2017 Feb;101(2):155-159), which concluded that Obstructive Sleep Apnoea (OSA) is not associated with Primary Open Angle Glaucoma (POAG). Potential POAG aetiology inflammatory markers are higher in OSA patients, and glaucoma diagnosis is more common in OSA populations.
While retrospective studies have great value, it is important to account for risk-associated conditions, including family history of OSA, racial disparities [1], smoking, hypertension, floppy eyelids, Type II diabetes [2], COPD and obesity.
To determine a causal relationship between OSA and POAG, it is necessary to assess intraocular pressures/visual field progression before and after continuous positive airway pressure (CPAP) treatment, using prospective randomised control trial designs. Further, the OSA base rate in Keenan et al. was 2.5%, while the estimated OSA prevalence rate may exceed 20% for those over 55 years of age [3]. Missing 90+% of apnoea sufferers may have blurred the true apnoea-POAG relationship. The risk rate for apnoea in the first year after initial POAG episode was 1.5, but declined to less than 1.0 in subsequent years, which suggests the possibility of increasing neglect of apnoea risk over the course of POAG. These findings highlight the lack of OSA screening and documentation, particularly in POAG sufferers, which should be confirmed with hypoxia measures that might better correlate with OSA pathology than other OSA diagnostic indices [4]. OSA risk screening tools (Berlin, STOPBANG sleep apnoea questionnaires) are readily available, are fast and simple to administer and score, and show acceptable rates of concordance with sleep study evidence of OSA [5]. We thank Keenan et al. for their important work and recommend a National OSA Screening program for all, including POAG patients.
References
1. O'Connor GT, Lind BK, Lee ET, Nieto FJ, Redline S, Samet JM, Boland LL, Walsleben JA, Foster GL; Sleep Heart Health Study Investigators.. Variation in symptoms of sleep-disordered breathing with race and ethnicity: the Sleep Heart Health Study. Sleep. 2003 Feb 1;26(1):74-9.
2. S.D. West, D.J. Nicoll, J.R. Stradling, Prevalence of obstructive sleep apnoea in men with type 2 diabetes, Thorax 61 (2006) 945–950.
3. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. The occurrence of sleep-disordered breathing among middle-aged adults. N Engl J Med. 1993 Apr 29;328(17):1230-5.
4. Bianchi MT, Russo K, Gabbidon H, Smith T, Goparaju B, Westover MB. Big data in sleep medicine: prospects and pitfalls in phenotyping. Nat Sci Sleep. 2017 Feb 16;9:11-29.
5. Nagappa M, Liao P, Wong J, Auckley D, Ramachandran SK, Memtsoudis S, Mokhlesi B, Chung F. Validation of the STOP-Bang Questionnaire as a Screening Tool for Obstructive Sleep Apnea among Different Populations: A Systematic Review and Meta-Analysis. PLoS One. 2015 Dec 14;10(12):e0143697.
I read with interest the article by Kuroda et al.[1] The authors
explored new possibilities of anterior segment imaging using a posterior
segment swept-source optical coherence tomography device without
noteworthy modifications. Interestingly, it was possible to obtain high-
resolution images of the conjunctiva, episclera, and the sclera near the
limbus that seemingly allow unequivocal identificati...
I read with interest the article by Kuroda et al.[1] The authors
explored new possibilities of anterior segment imaging using a posterior
segment swept-source optical coherence tomography device without
noteworthy modifications. Interestingly, it was possible to obtain high-
resolution images of the conjunctiva, episclera, and the sclera near the
limbus that seemingly allow unequivocal identification of anatomical
boundaries. The authors used this technique to examine eyes with anterior
scleritis/episcleritis.
However, I was not so impressed when I read through the methods
section of the paper. Contralateral eyes of patients were included as
controls. This is certainly problematic, considering that some of the
subjects had systemic inflammatory disease. In patients with overt
bilateral disease, both eyes were included in the analysis. As a result,
the measurements are not independent,[2] and the use of basic statistical
tests such as the Mann-Whitney or Kruskal-Wallis tests is not legitimate.
All these tests require independence of observations. Advanced statistical
methods[3] such as generalized estimating equations[4] or paired
comparison[5] would be necessary to obtain statistically valid results.
Another significant weakness of the methodology is that the thickness
of tissues was not measured perpendicularly to the ocular surface. This
makes data prone to bias and increases the variability. Moreover, the
internal limits of the sclera in Figures 2B and 4B are not very distinct,
and one wonders how accurate the measurements of this boundary are in
other eyes in the study, if these photos are representative.
To sum up, the images displayed are promising, yet, the scientific
rigour of the paper is much less compelling.
References
1. Kuroda Y, Uji A, Morooka S, et al. Morphological features in
anterior scleral inflammation using swept-source optical coherence
tomography with multiple B-scan averaging. Br J Ophthalmol Published
Online First: 7 July 2016. doi: 10.1136/bjophthalmol-2016-308561
2. Ray WA, O'Day DM. Statistical analysis of multi-eye data in
ophthalmic research. Invest Ophthalmol Vis Sci 1985; 26:1186-8.
3. Fan Q, Teo YY, Saw SM. Application of advanced statistics in
ophthalmology. Invest Ophthalmol Vis Sci 2011; 52:6059-65.
4. Hanley JA, Negassa A, Edwardes MD, et al. Statistical analysis of
correlated data using generalized estimating equations: an orientation. Am
J Epidemiol 2003; 157:364-75.
5. Murdoch IE, Morris SS, Cousens SN. People and eyes: statistical
approaches in ophthalmology. Br J Ophthalmol 1998; 82:971-3.
We thank Dr. Ebneter for his interest in our article.1 He pointed out
that we included contralateral eyes of unilateral diseased eyes as control
eyes and both eyes of bilateral affected eyes were included as diseased
eyes. Accordingly, we performed additional analyses. We excluded
contralateral eyes from control eyes and included only right eyes of
bilateral affected eyes as diseased eyes. As a resul...
We thank Dr. Ebneter for his interest in our article.1 He pointed out
that we included contralateral eyes of unilateral diseased eyes as control
eyes and both eyes of bilateral affected eyes were included as diseased
eyes. Accordingly, we performed additional analyses. We excluded
contralateral eyes from control eyes and included only right eyes of
bilateral affected eyes as diseased eyes. As a result, the average
thicknesses of conjunctival epithelium, conjunctival stroma/episclera
complex, and scleral stroma were 55.4?8.8, 288.0?44.4, and 434.2?60.1 ?m
in the control group, 52.2?8.8, 320.7?48.6, and 455.8?43.4 ?m in diffuse
episcleritis, 79.6?28.8, 450.7?138.3, and 469.5?41.7 ?m in diffuse
scleritis, respectively. Significant differences could be found in
conjunctival epithelium and conjunctival stroma/episclera complex among
the three groups (p=0.002, 0.001, Kruskal-Wallis test), but not in scleral
stroma (p=0.231). In diffuse scleritis, conjunctival epithelium and
conjunctival stroma/episclera complex were significantly thicker than in
controls (p=0.013 and 0.002). These results showed the same tendency as
the original results.
Second, Dr. Ebneter pointed out the weakness of the method, which is
that the thickness is measured vertically but not perpendicularly to the
ocular surface. We agree with him that this measurement method was crude
and moderately inaccurate. Unfortunately, we could not measure the
thickness in a direction perpendicular to conjunctival epithelium because
SS-OCT was used for the posterior segment. Moreover, he indicated that the
borders of the sclera in Figure 2B and 4B were vague. Indeed, it may not
be easy to clearly distinguish scleral stroma and episclera. Severe
thickening in the conjunctival stroma and episcleral layer may make the
border indistinct. However, the point of this article, which is that
thickening occurred mainly in the episclera rather than in the scleral
stroma in diffuse scleritis, was meaningful, even if the measurements were
crude.
References
1. Kuroda Y, Uji A, Morooka S, et al. Morphological features in
anterior scleral inflammation using swept-source optical coherence
tomography with multiple B-scan averaging. Br J Ophthalmol 2016. doi:
10.1136/bjophthalmol-2016-308561.
We read the article titled "Outcome of two-muscle surgery for large-
angle intermittent exotropia in children" by the authors Ki Won Jin and
Dong Gyu Choi with great enthusiasm.1 The authors have compared the
success of two muscle surgery for large angle (>=40 Prism Diopters
(PD)) vs moderate-angle (>=20 and <30PD) intermittent exotropia.
Neither of the two ranges described, include deviation between 30 to 39PD....
We read the article titled "Outcome of two-muscle surgery for large-
angle intermittent exotropia in children" by the authors Ki Won Jin and
Dong Gyu Choi with great enthusiasm.1 The authors have compared the
success of two muscle surgery for large angle (>=40 Prism Diopters
(PD)) vs moderate-angle (>=20 and <30PD) intermittent exotropia.
Neither of the two ranges described, include deviation between 30 to 39PD.
Whether these deviations were excluded or this is a typographical error is
subject to speculation. The range of exotropia in the large angle group
was upto 70PD. Several prior studies have shown that success rates of two
muscle surgery drop down significantly as the exotropia increases beyond
50PD2 and therefore three or four muscle surgery is recommended.3
Including such larger deviations skews the data and the chances of failure
automatically increases in Group A of the study. We believe that a better
comparison would have been between the moderate angle group and a second
group of 35 - 50PD.
None of the patients in the above study had symptomatic diplopia in
lateral gaze or palpebral fissure changes at any postoperative visit in
spite of performing large 9.5mm lateral rectus recession and 7mm medial
rectus recession in at least some of the patients. This observation is
unlike prior observations4 and our experience too with large recess-resect
surgery. Lastly the authors have not compared the two groups in terms of
refractive error which is an important factor leading to variations in
preoperative measurement of deviation and the effect of surgery.5
Nonetheless we would like to congratulate the authors for conducting this
important study that probably suggests that large angle intermittent
exotropia warrants more than two horizontal rectus muscle surgery in order
to achieve motor success in majority of patients.
Dear Editor,
We have read and reviewed the article entitled as "Choroidal structure in
eyes with drusen and reticular pseudodrusen determined by binarisation of
optical coherence tomographic images" by Corvi et al. with great interest
[1]. The authors compared luminal and stromal areas of the choroid in eyes
with drusen and reticular pseudodrusen (RPD), and investigated their
changes over 24 months using optical coherenc...
Dear Editor,
We have read and reviewed the article entitled as "Choroidal structure in
eyes with drusen and reticular pseudodrusen determined by binarisation of
optical coherence tomographic images" by Corvi et al. with great interest
[1]. The authors compared luminal and stromal areas of the choroid in eyes
with drusen and reticular pseudodrusen (RPD), and investigated their
changes over 24 months using optical coherence tomography (OCT). They
found that the mean total choroidal, luminal, and stromal areas decreased
similarly in eyes with drusen and RPD over the period of 24 months. The
mean total choroidal, luminal, and stromal areas were reduced more in eyes
with RPD when compared to the eyes with drusen, and the controls. We
express our gratitude to the authors for this valuable study, and we would
like to ask the authors some important points that may affect the study
results.
Owing to its unique anatomic structure, choroid is one of the most
excessively vascularized tissues in the body. Accordingly, various local,
systemic or environmental factors that affect vascular system influence
choroid [2,3]. Although Corvi et al. referred a number of factors
affecting choroid, we suggest that some important points should also be
addressed in the paper.
First, choroidal thickness (CT) has a significant diurnal variation.
Animal studies have demonstrated that CT might increase up to 50% in an
hour, and might decrease 100 ?m within 3-4 hours [3]. In a study, Usui et
al. analyzed subfoveal CT of healthy individuals at three hours intervals,
and discovered that CT demonstrated significant differences at all
measurement points [4]. In that study, Usui et al. indicated that diurnal
variation in CT might be up to 65 ?m (ranging between 8 and 65 ?m).
Another study by Lee et al. that included 100 adults reported the mean
amplitude of the diurnal variation in CT as 20.32 ? 10.40 ?m (ranging
between 4 and 60 ?m) [5]. Therefore we would like to ask the authors
whether they have considered diurnal variation of CT at baseline, and 24-
month choroid measurements.
Second, various systemic diseases (endocrine, cardiovascular,
rheumatologic, and inflammatory), and their medications may significantly
affect CT [2]. Since the participants of the study are old, those points
should be indicated in the paper.
Third, intraocular pressure and refractive status, which have well
known effects on CT, should be indicated in the paper, and compared
between the groups.
Fourth, we suggest that some important parameters that affect CT like
systemic blood pressure, and body mass index of the participants should
also be addressed in the paper. Moreover, alcohol, smoking, and
caffeinated beverage consuming of the participants should be asked for
before OCT measurements.
In summary, we suggest that the aforementioned factors affecting CT
may also affect stromal and luminal areas of the choroid as well, and
change the results of the study. We want to get the opinions of the
authors in this regard.
References
1 Corvi F, Souied EH, Capuano V, Costanzo E, Benatti L, Querques L, et al.
Choroidal structure in eyes with drusen and reticular pseudodrusen
determined by binarisation of optical coherence tomographic images. Br J
Ophthalmol. 2016; doi: 10.1136/bjophthalmol-2016-308548.
2 Tan KA, Gupta P, Agarwal A, Chhablani J, Cheng CY, Keane PA, et al.
State of science: Choroidal thickness and systemic health. Surv Ophthalmol
2016; doi: 10.1016/j.survophthal.2016.02.007.
3 Nickla DL, Wallman J. The multifunctional choroid. Prog Retin Eye Res
2010;29:144-68.
4 Usui S, Ikuno Y, Akiba M, Maruko I, Sekiryu T, Nishida K, et al.
Circadian changes in subfoveal choroidal thickness and the relationship
with circulatory factors in healthy subjects. Invest Ophthalmol Vis Sci
2012;53:2300-7.
5 Lee SW, Yu SY, Seo KH, Kim ES, Kwak HW. Diurnal variation in choroidal
thickness in relation to sex, axial length, and baseline choroidal
thickness
in healthy Korean subjects. Retina 2014;34:385-93.
We thank the authors[1] but wish to clarify several points. Stating that ‘glaucoma diagnosis is more common in OSA populations’ is controversial. Glaucoma diagnosis was not more common in our study (RR 1.01, CI 0.85-1.19), which censored prospectively from time of OSA coding throughout England from 1999-2011[2]. This is the largest and longest individual study conducted in this area. Several previous studies also observed no association.
The authors recommend accounting for ‘risk-associated conditions’. Accounting for potential confounders is important in evaluation of positive associations but less relevant in their absence. We agree that studies in different populations would be useful, particularly in Asia where OAG may differ.
In recommending a prospective RCT assessing ‘IOP/visual field progression before and after CPAP’, the authors are asking a different question. We have previously advocated this: ‘even in the absence of a positive association, it might still be relevant to identify those patients with genuine co-existence of OSA and POAG, particularly if evidence were to emerge … that OSA treatment could reduce glaucomatous progression’[2].
Our study never aimed to measure OSA point prevalence, so it is inappropriate to compare a speculative ‘base rate of 2.5%’ with prevalence estimates from a different continent/age-group. Moreover, our OSA cohort represented more severe disease; this should have exaggerated rather than ‘blurred’ any potentia...
Show MoreDear Sirs, We are grateful to Sabour and Ghassemi for their interest in our recent article[1]. In our understanding, they query why we did not use intra class correlation (ICC) as a measure for precision. Our test-retest reliability (absolute agreement ICC) is derived from the maximum likelihood (LM) estimates of the one-way random effects model of the form: yij...
Dear Editor
We were interested to read the approach taken by Sahni and Clark [1] to facilitate the effective Argon laser treatment of trichiasis. They have ably reviewed the complications of trichiasis, the different forms of management of trichiasis, the advantages of Argon laser treatment in the management of trichiasis, the technique of Argon laser trichiasis therapy, and the limitations of lash laser the...
Impact of initial visual acuity on anti-VEGF treatment outcomes in patients with macular oedema secondary to retinal vein occlusions in routine clinical practice Dan Calugaru, Mihai Calugaru Department of Ophthalmology, Univ of Medicine Cluj-Napoca/Romania Re: Impact of initial visual acuity on anti-VEGF treatment outcomes in patients with macular oedema secondary to retinal vein occlusions in routine clinical practice...
We have read with great interest Yokouchi et al’s article on the correlation between vascular endothelial growth factor (VEGF) levels and peripapillary retinal thickness in patients with POEMS syndrome(1) and we would like to share some reflections onthis mysterious form of optic neuropathy.
Show MoreThe acronym that gives name to the disorder does not include any ocular manifestation. However these patients frequently do develop ocular manifestations. Bilateral optic disc involvement appears in half of the patients and it has been considered an independent prognostic factor.(2)POEMS syndrome associated optic disc swelling constitutes a form of optic neuropathy that is not easy to classify. It is usually bilateral, but intracranial pressure is not elevated in most patients, so the term papilledema (although commonly used) is probably inaccurate. Most authors believe this optic neuropathy is related to increased VEGF levels, and Yokouchi et al’s work seems to support this theory.(1) From a pathogenic point of view optic disc swelling induced by cytokines should probably be considered a form of optic neuritis. However, inflammatory neuropathies often associate pain with eye movements and usually produce visual loss (reduced visual acuity and visual field damage) while POEMS patients present only minor visual disturbance and the visual prognosis is good.(3)
We suggest that POEMS associated optic disc swelling should be considered a new form of optic neuropathy. This neuro...
We read with great interest the article by Keenan et al. “Associations between obstructive sleep apnoea, primary open angle glaucoma and age-related macular degeneration: record linkage study” (Br J Ophthalmol. 2017 Feb;101(2):155-159), which concluded that Obstructive Sleep Apnoea (OSA) is not associated with Primary Open Angle Glaucoma (POAG). Potential POAG aetiology inflammatory markers are higher in OSA patients, and glaucoma diagnosis is more common in OSA populations.
While retrospective studies have great value, it is important to account for risk-associated conditions, including family history of OSA, racial disparities [1], smoking, hypertension, floppy eyelids, Type II diabetes [2], COPD and obesity.
To determine a causal relationship between OSA and POAG, it is necessary to assess intraocular pressures/visual field progression before and after continuous positive airway pressure (CPAP) treatment, using prospective randomised control trial designs. Further, the OSA base rate in Keenan et al. was 2.5%, while the estimated OSA prevalence rate may exceed 20% for those over 55 years of age [3]. Missing 90+% of apnoea sufferers may have blurred the true apnoea-POAG relationship. The risk rate for apnoea in the first year after initial POAG episode was 1.5, but declined to less than 1.0 in subsequent years, which suggests the possibility of increasing neglect of apnoea risk over the course of POAG. These findings highlight the lack of OSA screening and...
Show MoreDear Editor,
I read with interest the article by Kuroda et al.[1] The authors explored new possibilities of anterior segment imaging using a posterior segment swept-source optical coherence tomography device without noteworthy modifications. Interestingly, it was possible to obtain high- resolution images of the conjunctiva, episclera, and the sclera near the limbus that seemingly allow unequivocal identificati...
Dear Editor:
We thank Dr. Ebneter for his interest in our article.1 He pointed out that we included contralateral eyes of unilateral diseased eyes as control eyes and both eyes of bilateral affected eyes were included as diseased eyes. Accordingly, we performed additional analyses. We excluded contralateral eyes from control eyes and included only right eyes of bilateral affected eyes as diseased eyes. As a resul...
We read the article titled "Outcome of two-muscle surgery for large- angle intermittent exotropia in children" by the authors Ki Won Jin and Dong Gyu Choi with great enthusiasm.1 The authors have compared the success of two muscle surgery for large angle (>=40 Prism Diopters (PD)) vs moderate-angle (>=20 and <30PD) intermittent exotropia. Neither of the two ranges described, include deviation between 30 to 39PD....
Dear Editor, We have read and reviewed the article entitled as "Choroidal structure in eyes with drusen and reticular pseudodrusen determined by binarisation of optical coherence tomographic images" by Corvi et al. with great interest [1]. The authors compared luminal and stromal areas of the choroid in eyes with drusen and reticular pseudodrusen (RPD), and investigated their changes over 24 months using optical coherenc...
Pages