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• B-scan ultrasound, visual electrophysiology and perioperative videoendoscopy for predicting functional results in keratoprosthesis candidates
  Lauro A. OLIVEIRA, Luzia D. Silva, Flavio E. Hirai, Norma Allemann, Adriana Berezovsky, Solange R. Salomão, Paulo R. C. Oliveira, Gabriel C. Andrade, Andre Maia and Luciene B. Sousa
  Published on: 16 December 2021
• B-scan ultrasound, visual electrophysiology and perioperative videoendoscopy for predicting functional results in keratoprosthesis candidates
  Sonia Anchouche, Mona Harissi-Dagher
  Published on: 16 December 2021

• Published on: 16 December 2021

  B-scan ultrasound, visual electrophysiology and perioperative videoendoscopy for predicting functional results in keratoprosthesis candidates

  • Lauro A. OLIVEIRA, Affiliate Professor at Department of Ophthalmology and Visual Sciences - Federal University of São Paulo - Brazil Department of Ophthalmology and Visual Sciences, Federal University of São Paulo, Brazil
  • Other Contributors:
    • Luzia D. Silva, Medical assistant at the Department of Ophthalmology and Visual Sciences, Federal University of São Paulo, Brazil
    • Flavio E. Hirai, Head of Ocular External Diseases and Cornea - Department of Ophthalmology and Visual Sciences, Federal University of São Paulo,
    • Norma Allemann, Adjunct Professor at Department of Ophthalmology and Visual Sciences, Federal University of São Paulo, Brazil
    • Adriana Berezovsky, Adjunct Professor at Department of Ophthalmology and Visual Sciences, Federal University of São Paulo, Brazil
    • Solange R. Salomão, Adjunct Professor at Department of Ophthalmology and Visual Sciences, Federal University of São Paulo, Brazil
    • Paulo R. C. Oliveira, Ophthalmologist
    • Gabriel C. Andrade, Ophthalmologist
    • Andre Maia, Ophthalmologist
    • Luciene B. Sousa, Ophthalmologist

  Luzia Diegues Silva MD1, Albert Santos MD1, Flávio Eduardo Hirai MD. Ph.D1, Norma Allemann MD1,2, Adriana Berezovsky Ph.D1, Solange Rios Salomão Ph.D1, Paulo Ricardo Chaves de Oliveira MD1, Gabriel Costa de Andrade MD1, Andre Maia MD1, Luciene Barbosa de Sousa MD1, Lauro Augusto de Oliveira MD. Ph.D.1,*

  1 Department of Ophthalmology and Visual Sciences, Federal University of São Paulo, Brazil
  2 Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, USA
  Corresponding author: Lauro Augusto de Oliveira

  Dear Editor,

  We read with interest the comments about our article by Anchouche and associates.

  We agree with the authors that B-scan ultrasonography is widely accepted as the gold-standard preoperative imaging modality used to assess the posterior segment in eyes with severe and dense anterior segment opacities and it has been proven to be a useful tool in the preoperative evaluation of Kpro candidates. We also agree that it is safer, cheaper and a less invasive procedure when compared to VE. However, this image modality offers mostly anatomical information and less functional prognosis prediction when compared to direct visualization of the posterior segment achieved with VE.[1]

  We are aware and agree with the authors’ concern regarding the invasive nature, the risk of elevated intraocular pressure, and cataract formation as discussed in our work. However, as it is clearly described in our manuscript,...

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  Luzia Diegues Silva MD1, Albert Santos MD1, Flávio Eduardo Hirai MD. Ph.D1, Norma Allemann MD1,2, Adriana Berezovsky Ph.D1, Solange Rios Salomão Ph.D1, Paulo Ricardo Chaves de Oliveira MD1, Gabriel Costa de Andrade MD1, Andre Maia MD1, Luciene Barbosa de Sousa MD1, Lauro Augusto de Oliveira MD. Ph.D.1,*

  1 Department of Ophthalmology and Visual Sciences, Federal University of São Paulo, Brazil
  2 Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, USA
  Corresponding author: Lauro Augusto de Oliveira

  Dear Editor,

  We read with interest the comments about our article by Anchouche and associates.

  We agree with the authors that B-scan ultrasonography is widely accepted as the gold-standard preoperative imaging modality used to assess the posterior segment in eyes with severe and dense anterior segment opacities and it has been proven to be a useful tool in the preoperative evaluation of Kpro candidates. We also agree that it is safer, cheaper and a less invasive procedure when compared to VE. However, this image modality offers mostly anatomical information and less functional prognosis prediction when compared to direct visualization of the posterior segment achieved with VE.[1]

  We are aware and agree with the authors’ concern regarding the invasive nature, the risk of elevated intraocular pressure, and cataract formation as discussed in our work. However, as it is clearly described in our manuscript, the VE test was performed perioperatively and did not hinder the surgical decision to proceed with KPro surgery. There was no additional anesthesia risk. Cataract formation was not a concern in this scenario because all Kpro candidates in our series would have their lens removed.
  The study does have limitations such as the sample size. But this series allowed for an overall better understanding of the endoscopic findings and their usefulness, particularly with the comparative metrics between the preoperative data and postoperative results.

  Optimizing the use of keratoprosthesis as an alternative for corneal blindness is challenging in contexts in which the device is not available or affordable. This is a difficult decision faced by surgeons daily, especially in limited-resource settings such as ours. We will continue to investigate strategies for predicting prognosis to allow us to be more precise in the selection of treatment. We agree with the authors that our findings should not be over-generalized. Ideally one cannot deny keratoprosthesis implantation based on unfavourable findings noted on videoendoscopy, but regarding prognostication, we would counsel these patients on potential visual outcomes.

  1. Farias CC, Ozturk HE, Albini TA, et al. Use of intraocular video endoscopic examination in the preoperative evaluation of keratoprosthesis surgery to assess visual potential. Am J Ophthalmol 2014;158:80-6.

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  Conflict of Interest:
  None declared.

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• Published on: 16 December 2021

  B-scan ultrasound, visual electrophysiology and perioperative videoendoscopy for predicting functional results in keratoprosthesis candidates

  • Sonia Anchouche, MD Candidate Faculty of Medicine, McGill University, Montreal, QC, Canada
  • Other Contributors:
    • Mona Harissi-Dagher, Chief of Cornea Service and Full Professor

  Dear Editor,

  We read with interest the study by Silva and colleagues.[1] The authors investigate the prognostic potential of B-scan ultrasonography, visual electrophysiology and perioperative videoendoscopy (VE) for 13 patients undergoing keratoprosthesis (KPro) surgery and identified perioperative intraocular VE as a predictor of functional visual outcome at 1-year follow-up.[1] While we find this study interesting, we would like to caution against the interpretation and over-generalization of the findings reported therein.

  Negative predictive value (NPV) was as defined as the number of patients with abnormal VE findings and subsequent unsatisfactory visual acuity over all patients with unfavourable VE. The authors report a NPV of 50% in 10 patients. By contrast, they report a positive predictive value (PPV) of 100% for this test.[1] Although a high PPV, as reported by the authors, is of great importance when deciding which patients are appropriate KPro candidates preoperatively, once the patient is undergoing surgery, we believe identifying patients at highest risk of poor visual outcome using NPV is more clinically relevant. The small sample size of 10 patients with a low prevalence of patients with unsatisfactory post-operative visual acuity, and NPV of 50% are important limitations of this study. From these findings, we are unable to justify VE's clinical benefit to the surgeon and their patient at the time of surgery. This is especially true give...

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  Dear Editor,

  We read with interest the study by Silva and colleagues.[1] The authors investigate the prognostic potential of B-scan ultrasonography, visual electrophysiology and perioperative videoendoscopy (VE) for 13 patients undergoing keratoprosthesis (KPro) surgery and identified perioperative intraocular VE as a predictor of functional visual outcome at 1-year follow-up.[1] While we find this study interesting, we would like to caution against the interpretation and over-generalization of the findings reported therein.

  Negative predictive value (NPV) was as defined as the number of patients with abnormal VE findings and subsequent unsatisfactory visual acuity over all patients with unfavourable VE. The authors report a NPV of 50% in 10 patients. By contrast, they report a positive predictive value (PPV) of 100% for this test.[1] Although a high PPV, as reported by the authors, is of great importance when deciding which patients are appropriate KPro candidates preoperatively, once the patient is undergoing surgery, we believe identifying patients at highest risk of poor visual outcome using NPV is more clinically relevant. The small sample size of 10 patients with a low prevalence of patients with unsatisfactory post-operative visual acuity, and NPV of 50% are important limitations of this study. From these findings, we are unable to justify VE's clinical benefit to the surgeon and their patient at the time of surgery. This is especially true given the invasive nature, cost and associated complications of this ancillary test. In addition to the risk of elevated intraocular pressure and cataract formation as outlined by the authors, the use of perioperative VE increases the risk of iatrogenic retinal tears, vitreous hemorrhage, and wound leaks,[2] not to mention the risk of retrobulbar anaesthesia,[3] all of which are morbid complications in KPro eyes. Moreover, 23% of the patient cohort (n=3) were excluded from analysis due to technical issues relating to perioperative VE. This highlights the additional challenges this ancillary test may present to the surgeon and their team.

  Although prognosticating the visual outcomes of KPro and identifying which patients are at highest risk of KPro failure remain important areas of research and discussion, we believe the data presented by the authors are insufficient to position VE as a predictive perioperative ancillary test and urge readers to consider the associated risks to the patient and medical costs to the healthcare system. B-scan ultrasonography is widely accepted as the gold-standard preoperative imaging modality used to assess the posterior segment in eyes with severe and dense anterior segment opacities.[4] After reading this study, we believe that B-scan ultrasonography remains the method of choice for KPro preoperative evaluations.

  References:
  1. Silva, L. D. et al. B-scan ultrasound, visual electrophysiology and perioperative videoendoscopy for predicting functional results in keratoprosthesis candidates. Br. J. Ophthalmol. (2020).
  2. Nagiel, A. et al. VISUAL AND ANATOMIC OUTCOMES OF PEDIATRIC ENDOSCOPIC VITRECTOMY IN 326 CASES. Retina (2020).
  3. Hamilton, R. C. A discourse on the complications of retrobulbar and peribulbar blockade. Can. J. Ophthalmol. (2000).
  4. Williamson, S. L. & Cortina, M. S. Boston type 1 keratoprosthesis from patient selection through postoperative management: A review for the keratoprosthetic surgeon. Clinical Ophthalmology (2016).

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  Conflict of Interest:
  None declared.

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