Corneal Neurotization: Preoperative Patient Workup and Surgical Decision-making.

Background: The use of sensory nerve transfers to the anesthetic cornea has transformed the treatment of neurotrophic keratopathy by restoring ocular surface sensation and activating dysfunctional epithelial repair mechanisms. However, despite numerous reports on surgical techniques, there is a scarcity of information on the interdisciplinary management, preoperative assessment, and surgical decision-making, which are equally critical to treatment success. Methods: This Special Topic presents a standardized, interdisciplinary preoperative workup based on our 10-year experience with corneal neurotization in 32 eyes of patients with neurotrophic keratopathy. Results: Our assessment includes a medical history review, ophthalmic evaluation, and systematic facial sensory donor nerve mapping for light touch and pain modalities. This approach enables evidence-based patient selection, optimal surgery timing, and suitable donor nerve identification, including backup options. Conclusions: Based on a decade-long experience, this special topic highlights the importance of interdisciplinary collaboration and provides a practical roadmap for optimizing patient selection and surgical decision-making in patients undergoing corneal neurotization.

Children with high astigmatism: tomographic and refractive characteristics and the ability of current indices to rule out keratoconus.

PURPOSE: To assess corneal tomographic, topographic, and refractive changes in children with high astigmatism and their ability to exclude keratoconus. METHODS: In this longitudinal observational study, the medical records of children with high regular cylindrical refraction of ≥3.50 D referred to the Hospital for Sick Children, Toronto, to exclude keratoconus between January 2009 and June 2020 were reviewed retrospectively. Corneal tomography records (Scheimpflug imaging) were reviewed for subjects with total astigmatism of ≥ +3.50 D by retinoscopy. Children with abnormal anterior segment examination and/or other risk factors for corneal disease or ectasia and those with unreliable corneal tomography were excluded. Baseline demographic, longitudinal tomographic, topographic, and refractive data were analyzed. RESULTS: A total of 67 eyes of 37 children (mean age, 9.1 ± 3.5 years) were included. Mean cylindrical refraction at presentation was 5.10 ± 1.30 D. Mean follow-up was 2.3 ± 1.8 years. Twenty-nine eyes had Kmax ≥47.20 D at baseline, with no change at last follow-up. Ksteep, Kmax, and thinnest pachymetry were 46.44 ± 2.33 D, 47.06 ± 2.57 D, and 525.86 ± 35.45 µm, respectively, at baseline compared with 46.40 ± 2.28 D, 46.98 ± 2.40 D, and 527.61 ± 37.67 µm at last follow-up (P > 0.05). All eyes were predicted as not having keratoconus using inferior-superior dioptric asymmetry ratio (I-S ratio), and the keratometry, inferior-superior, and astigmatism index (KISA%), which also incorporates skew percentage. The other tomographic indices predicted keratoconus or subclinical keratoconus in at least 22.4% of eyes. All parameters did not significantly change during follow-up. CONCLUSIONS: In the absence of other risk factors for keratoconus, children with high regular astigmatism demonstrated clinical and tomographic stability over time. Based on our results, we recommend that I-S ratio and KISA% be primarily used when monitoring normal children with high astigmatism to rule out keratoconus-related changes.

Keratopathy in Noonan Syndrome.

PURPOSE: Anterior segment abnormalities associated with Noonan syndrome are rare. We report our experience with 2 patients who developed keratopathy with significant visual sequelae. METHODS: case series. RESULTS: The first patient is a 9-year-old boy with genetically confirmed Noonan syndrome. At presentation, he was noted to have diffuse inferior epitheliopathy with vascularization and bilateral mild ptosis. Over 1 year, he developed focal areas of scarring with deterioration of vision and underwent superficial keratectomy in the left eye. However, over the following 2 years, he experienced recurrent corneal scarring and vascularization. The second patient is a 7-year-old boy with phenotypic Noonan syndrome. At presentation, he had an anterior subepithelial corneal scar inferiorly with epithelial defects in both eyes. He also had bilateral moderate ptosis and lagophthalmos. Despite lubrication, he developed recurrent bilateral corneal erosions with focal areas of scarring associated with vascularization and underwent superficial keratectomy for both eyes. Despite this, there was worsening corneal scarring and vascularization over time, eventually requiring deep anterior lamellar keratoplasty in the left eye. The host cornea showed a disturbed Bowman layer and an acellular mass of fibrous collagenous tissue between epithelium and stroma. CONCLUSIONS: Noonan syndrome may be associated with visually significant keratopathy, manifesting as focal corneal scarring with vascularization. These changes may due to an excessive fibrotic response in Noonan syndrome. Early recognition and treatment can help to delay the progression of keratopathy and need for surgical intervention.

Minimally Invasive Corneal Neurotization Provides Sensory Function, Protects Against Recurrent Ulceration, and Improves Visual Acuity.

PURPOSE: To measure sensory recovery after minimally invasive corneal neurotization, and to identify and quantify the extent to which patient and technical factors influence sensory recovery, ulceration rate, and visual outcomes. DESIGN: Retrospective case series. METHODS: This study included 23 patients with neurotrophic keratopathy who underwent indirect corneal neurotization. The primary outcome measure was corneal sensitivity with Cochet-Bonnet aesthesiometry (CBA), and the secondary outcome measure was epithelial breakdown. RESULTS: Over a 7-year period, 28 eyes of 23 patients (mean age, 15.6 ± 13.6 years) were included in the study. The CBA measurements improved from 3.5 ± 9.1 mm at baseline to 44.1 ± 18.2 mm at 24 months after surgery (P < .001). Maximum CBA was reached after 11.1 ± 6.2 months (median, 9 months). Compared to eyes neurotized with a contralateral donor nerve, eyes with an ipsilateral donor nerve achieved a higher mean CBA (36.0 ± 10.9 vs 10.4 ± 14.0 mm, P = .001) at 3 months. Both the number of fascicles (Spearman correlation coefficient, rs -0.474, P = .11) and insertions (rs -0.458, P = .014) negatively correlated with the final CBA. Nine eyes (32.1%) experienced at least 1 episode of epithelial breakdown after surgery. Visual acuity improved in the neurotized corneas from logMAR 0.57 ± 0.79 at baseline to 0.39 ± 0.66 at 12 months (P = .043). CONCLUSIONS: Corneal sensation improves over time after corneal neurotization. There is resultant improvement in visual acuity and protection against epithelial breakdown. It is important to maximize sensory recovery to protect against recurrent ulceration.

Endothelial keratoplasty with anterior chamber intraocular lens versus secondary posterior chamber intraocular lens.

AIM: To describe the long-term outcomes of Descemet stripping automated endothelial keratoplasty (DSAEK) with an anterior chamber intraocular lens (ACIOL) compared to secondary posterior chamber (PC) IOL. METHODS: This was a retrospective comparative cohort study. The clinical data of 82 eyes from 82 consecutive patients with pseudophakic (PBK) or aphakic bullous keratopathy (ABK) who either underwent DSAEK with retained or secondary ACIOL (n=23) or DSAEK with IOL exchange and/or secondary PCIOL (retropupillary iris-claw IOL, n=25; intrascleral-fixated IOL, n=29; or sulcus IOL, n=5) were analysed. The main outcome measures were graft survival and complications up to 5 years. RESULTS: The graft survival in the secondary PCIOL group was superior than the ACIOL group over 5 years (year 1, 100.0% vs 100.0%; year 3, 94.7% vs 75.0%; year 5, 91.1% vs 60.6%, p=0.022). The presence of an ACIOL was a significant risk factor associated with graft failure (HR, 4.801; 95% CI, 1.406 to 16.396, p=0.012) compared to a secondary PCIOL. There was no significant difference in the rate of graft detachment and elevated intraocular pressure between the groups. There were five cases (9.3%) of IOL subluxation or dislocation in the retropupillary iris-claw and intrascleral-fixated IOL groups. CONCLUSIONS: Eyes that underwent DSAEK with ACIOL in situ had poorer long-term graft survival compared with those with secondary PCIOL. Intraocular lens exchange was not associated with a higher complication rate. In ABK or PBK eyes with ACIOL, we recommend performing IOL exchange and/or secondary PCIOL implantation combined with endothelial keratoplasty.

Hybrid Descemet Membrane Endothelial Keratoplasty (H-DMEK): results of a donor insertion pull-through technique using donor stroma as carrier.

AIM: To evaluate the outcomes and complications of hybrid Descemet membrane endothelial keratoplasty (H-DMEK) using a Descemet stripping automated endothelial keratoplasty (DSAEK) pull-through donor inserter and donor stroma as carrier. METHODS: This was a retrospective interventional case series of eyes with bullous keratopathy (BK) and Fuchs endothelial corneal dystrophy (FECD), which underwent H-DMEK, performed using a bimanual pull-through technique using DSAEK-prepared donor stroma as carrier and the EndoGlide Ultrathin DSAEK donor insertion device. Complex cases with tube shunts, trabeculectomy, aphakia, aniridia, previous vitrectomy, keratoplasty or combined with intraocular lens exchange, were also included. The outcome measures were intraoperative and postoperative complications, best corrected visual acuity (BCVA) and endothelial cell loss after surgery. RESULTS: Of the 85 eyes from 79 patients, 43.5% (n=37) had BK, 28.2% (n=24) had FECD while 24.7% (n=21) had failed grafts. DMEK was performed in 37 complex eyes (43.5%). Four eyes (4.7%) required rebubbling for graft detachment and two cases of graft failure were observed. A BCVA of 20/25 or better was attained in 44.7% and 57.1% of eyes without pre-existing ocular pathology at 6 and 12 months, respectively. The overall endothelial cell loss was 32.2%±20.5% at 6 months, which improved from 37.2%±20.9% to 24.2%±17.5%, comparing the first 40 and last 45 cases (p=0.012). CONCLUSION: Hybrid DMEK offers a controlled 'pull-through' technique of donor insertion in the 'endothelium-in' configuration, which may be useful especially in complicated eyes. More studies are needed to confirm the long-term endothelial cell loss and graft survival associated with this technique.

Outcomes of Repeat Anterior Lamellar Keratoplasty.

PURPOSE: To describe the outcomes and complications of repeat anterior lamellar keratoplasty (ALK) after a failed primary ALK. METHODS: This was a retrospective case series. Twenty-three eyes of 22 patients who underwent repeat ALK for optical indications from January 1, 1991, to December 31, 2017, were included. Clinical data were recorded from the Singapore Corneal Transplant Study database. Outcome measures were graft survival, best-corrected visual acuity (BCVA), and complications. RESULTS: Of the 780 cases of ALK performed for optical indications during the study period, 23 cases (2.9%) underwent repeat ALK. Primary ALK comprised of 16 deep ALK and 7 automated lamellar therapeutic keratoplasty cases. After repeat ALK, 21 eyes had further dissection down to the descemetic or predescemetic plane, whereas 2 eyes had graft exchange for failed automated lamellar therapeutic keratoplasty. The graft survival of repeat ALK was 93.2%, 86.1%, and 78.3% at 1, 3, and 5 years, respectively. There were 4 cases of graft failure with a mean time to failure of 2.0 ± 1.7 years. After the repeat ALK procedure, 63.6% and 66.7% of eyes achieved a BCVA of LogMAR +0.3 (20/40) or better at 1 and 2 years, respectively. Five eyes (17.4%) had an intraoperative microperforation. CONCLUSIONS: In the case of a failed ALK graft for a range of optical indications, a repeat ALK procedure offers a viable and safe surgical option with good long-term graft survival and visual outcomes, while avoiding the various disadvantages of performing penetrating keratoplasty, especially the risk of allograft endothelial rejection.

Descemet Membrane Endothelial Keratoplasty Versus Descemet Stripping Automated Endothelial Keratoplasty and Penetrating Keratoplasty.

PURPOSE: To compare the long-term graft survival outcomes and complications of patients who underwent Descemet membrane endothelial keratoplasty (DMEK), Descemet stripping automated endothelial keratoplasty (DSAEK), and penetrating keratoplasty (PK) for Fuchs endothelial corneal dystrophy (FECD) and bullous keratopathy (BK). DESIGN: Retrospective comparative cohort study. METHODS: Patients with FECD and BK who underwent DMEK (121 eyes), DSAEK (423 eyes), or PK (405 eyes) from the prospective cohort from the Singapore Corneal Transplant Registry were included. A Kaplan-Meier survival analysis was conducted to compare the survival probabilities of the 3 groups. The main outcome measure was graft survival. RESULTS: The DMEK group had the best overall cumulative graft survival of 97.4%, compared to DSAEK (78.4%) and PK (54.6%) (P < .001). In eyes with FECD, the DMEK group had the best graft survival of 98.7% compared to DSAEK (96.2%) and PK (73.5%) (P = .009). The graft survival in eyes with BK was poorer overall; however, the DMEK group still had the best graft survival of 94.7%, compared to DSAEK (65.1%) and PK (47.0%, P = .001). Eyes that underwent DMEK had the lowest rate of graft rejection (1.7% vs DSAEK 5.0% vs PK 14.1%, P < .001) and postoperative elevation of intraocular pressure (11.6% vs DSAEK 23.6% vs PK 22.5%, P = .015). CONCLUSIONS: Patients who underwent DMEK for FECD and BK had better graft survival compared to DSAEK and PK. Eyes that underwent DMEK also had a significantly lower rate of graft rejection and elevated intraocular pressure compared to DSAEK and PK for the same indications.

Conventional Versus Accelerated Collagen Cross-Linking for Keratoconus: A Comparison of Visual, Refractive, Topographic and Biomechanical Outcomes.

OBJECTIVE: The aim was to compare the visual, refractive, topographic and biomechanical outcomes in patients with progressive keratoconus treated with either conventional or accelerated crosslinking at one year follow up. METHODS: It is a prospective, non-randomised interventional study of 76 patients who underwent conventional (CXL; 3mW/cm2 for 30 minutes) or accelerated cross linking (KXL; 30mW/cm2 for 4 minutes) for progressive keratoconus. Baseline and postoperative visual acuity, manifest refraction, corneal topography, pachymetry, endothelial cell density and biomechanical parameters of corneal hysteresis and corneal resistance factor were evaluated and compared. RESULTS: The 2 groups were comparable in terms of uncorrected and best corrected visual acuity and spherical equivalent. Both groups showed no significant increase in K1, K2 and Kmean from baseline at 12 months. There was also no difference between the CXL and KXL group for postoperative corneal topography as well as central and minimal pachymetry up to 12 months. There was a significant increase in both corneal hysteresis (0.62mm Hg, P=0.04) and corneal resistance factor (0.91mm Hg, P=0.003) in the KXL group at 12 months but not in the CXL group. There was no significant endothelial cell loss throughout follow up in both the groups. CONCLUSION: We have established comparability of the 2 protocols in stabilizing the progression of keratoconus. Our findings also suggested an added biomechanical advantage of accelerated crosslinking at 1 year follow up.

Perioperative glycaemic control in diabetic patients undergoing cataract surgery under local anaesthesia: a survey of practices of Singapore ophthalmologists and anaesthesiologists.

INTRODUCTION: Perioperative glycaemic control is an important aspect of clinical management in diabetic patients undergoing cataract surgery under local anaesthesia. While poor long-term glycaemic control has significant implications for surgery, perioperative hypoglycaemia or hyperglycaemia may also compromise patient safety and surgical outcomes. We aimed to survey ophthalmologists and anaesthesiologists on their approach and to identify the prevalent practice patterns in Singapore. METHODS: This was a cross-sectional questionnaire-based survey conducted in four public hospitals in Singapore with established ophthalmology and anaesthesia units. Respondents were approached individually, and the self-administered questionnaires comprised questions related to practice patterns, clinical scenarios and awareness of pre-existing guidelines. RESULTS: A total of 129 doctors responded to the questionnaire survey. 76 (58.9%) were from ophthalmology departments and 53 (41.1%) were from anaesthesia departments. The majority chose to withhold oral hypoglycaemic agents (82.9%) and/or insulin (69.8%), and keep the patient fasted preoperatively. A blood glucose level ≥ 17 mmol/L prompted 86.0%-93.8% of respondents to adopt a treat-and-defer strategy, while a level ≥ 23 mmol/L prompted 86.0%-96.9% of respondents to cancel the cataract surgery. The respondents were consistently more concerned about perioperative hyperglycaemia (n = 99, 76.7%) than intraoperative hypoglycaemia (n = 83, 64.3%). CONCLUSION: The current study presented the prevalent practice patterns of ophthalmologists and anaesthesiologists in the perioperative management of diabetic patients undergoing cataract surgery in four public hospitals in Singapore. Further research in this field is required, and may be useful for the future formulation of formal guidelines and protocols.

Characteristics of Cytomegalovirus Uveitis in Immunocompetent Patients.

PURPOSE: To present the clinical characteristics of patients with anterior uveitis who had evidence of cytomegalovirus (CMV) infection on polymerase chain reaction PCR-based assays for viral DNA in aqueous samples. METHODS: This was a retrospective observational case series of 16 patients with CMV infection on qualitative polymerase chain reaction PCR-based assays for viral DNA in aqueous samples. Case records of 16 patients were reviewed and relevant clinical information was collected using a standardized data sheet. RESULTS: There were 10 male and 6 female patients, with 16 eyes included. The median age at the first attack was 52 years (range 27-77 years). Thirteen patients (81.3%) presented with an initial BCVA of 20/40 or better. Eleven eyes (68.8%) had anterior chamber inflammation of 1+ cells or less. Eight eyes (50.0%) had concomitant sectoral iris atrophy, while 2 eyes were noted to have heterochromic irides. Eleven patients (68.8%) presented with an elevated intraocular pressure. Seven patients (43.8%) had clinical features that led to a presumptive diagnosis of Posner-Schlossman syndrome, while 3 patients (18.8%) were initially diagnosed with Fuchs heterochromic iridocyclitis. Six patients were initially treated for uveitic glaucoma or anterior uveitis of unknown cause. CONCLUSIONS: There is a spectrum of clinical manifestations of CMV anterior uveitis. A high index of suspicion of a possible viral etiology, especially CMV, and subsequent accurate identification of the virus involved are fundamental to the overall therapeutic approach.

The epidemiology of age-related macular degeneration in the Indian subcontinent.

CONTEXT: The Indian subcontinent is one of the most populous regions in the world. Given the projected rapid population growth and ageing of the population, age-related macular degeneration (AMD) is likely to emerge as a major public health threat in the near future. However, existing literature on AMD in the region is scarce. METHODS: This paper reviews the epidemiology and risk factors of AMD in the Indian subcontinent. RESULTS: Data on AMD in India show prevalences ranging from 1.8% to 4.7%. Blindness prevalence studies in Pakistan, Bangladesh and Nepal have also reported rates of 2.1% to 8.7% for all blindness attributable to AMD. Age-related macular degeneration is therefore a significant cause of visual morbidity in these countries. To date, no reliable epidemiological data on AMD or blindness have been published for Sri Lanka, Afghanistan, Maldives or Bhutan. CONCLUSIONS: The prevalence of AMD in the region is likely to follow a trend similar to that seen in the developed world in the coming years. Eye care policies should therefore make provisions for this chronic age-related eye disease. In addition, there is an urgent need for more data on the epidemiology of AMD in the Indian subcontinent.

Eye injuries in Singapore--don't risk it. Do more. A prospective study.

INTRODUCTION: The purpose of this study was to characterise and describe the epidemiology of all eye injuries presenting to the National University Hospital (NUH). MATERIALS AND METHODS: A prospective study was conducted over a 7-week period (11/4/2005 to 29/5/2005) on all ophthalmic trauma patients seen by the Department of Ophthalmology in NUH. Data on patient presentation, source of injury and intervention were collected via a standardised interview and examination, and documented using a validated datasheet. RESULTS: A total of 133 patients, and 139 eyes, were included in the study. The average age was 33.5 years, with a range of 5 years to 88 years, and 84.2% (n = 112) were men. Close to half (46.6%, n = 62) of the patients studied were non-Singaporeans. 56.4% (n = 75) of all eye injuries were work-related and only 5% (n = 7) of eyes were open-globe injuries. Common sources of eye trauma included: Use of high-powered tools in activities such as grinding, welding and hammering (38.3%, n = 51), human-inflicted injuries (12.0%, n =16) and road traffic accidents (8.3%, n = 11). Of the work-related eye injuries, 29.3% (n = 22) reported to having used personal protective equipment (PPE) at the time of injury, 38.7% (n = 29) had been issued PPE but had not used them, while 32% (n = 24) reported that PPE had not been issued. An initial visual acuity of 6/12 or better was found in 63.0% (n = 88) of patients and a reading of 6/60 or worse was found in 10.0% (n =14). Superficial foreign bodies (22.4%, n = 55) were the most common clinical finding, followed by periorbital bruise (12.2%, n = 30), lid ecchymoses (6.9%, n = 17), orbital fractures (6.5%, n = 16), lid laceration (6.1%, n = 15) and corneal abrasions (5.7%, n = 14). CONCLUSION: There is a broad spectrum of causes, mechanisms and severity of ophthalmic injuries seen in the hospital, of which work-related trauma makes up a significant proportion. The patients who suffer occupational injuries are a well-defined group: Young, non-Singaporean males, working with power tools in the construction industry are at particular risk. Although preventive strategies are in place for this high-risk group, the lack of awareness and compliance limit their effectiveness. The adequacy and functionality of PPE should be emphasised. In addition, preventive efforts are equally important in domestic, recreational, sports and transport settings. Eye trauma research and prevention can be further aided by a collaborative registry of eye injuries. A long-term islandwide database of all ophthalmic injuries is recommended.