Management of corneal perforations in dry eye disease: Preferred practice pattern guidelines

Corneal perforations in eyes with dry eye disease (DED) are difficult to manage due to the interplay of several factors such as the unstable tear film, surface inflammation, and the underlying systemic disease affecting the wound healing process, and the eventual outcome. A careful preoperative examination is required to identify the underlying pathology, and status of ocular surface and adnexa, rule out microbial keratitis, and order appropriate systemic workup in addition to assessing the perforation itself. Several surgical options are available, which include tissue adhesives, multilayered amniotic membrane grafting (AMT), tenon patch graft (TPG), corneal patch graft (CPG), and penetrating keratoplasty (PK). The choice of procedure depends upon the size, location, and configuration of the perforation. In eyes with smaller perforations, tissue adhesives are effective treatment modalities, whereas AMT, TPG, and CPG are viable options in moderate-sized perforations. AMT and TPG are also preferable in cases where the placement of a bandage contact lens may be a challenge. Large perforations require a PK, with additional procedures such as tarsorrhaphy to protect the eyes from the associated epithelial healing issues. Conjunctival flaps are considered in eyes with poor visual potential. The management of the acute condition is carried out in conjunction with measures to improve the tear volume bearing in mind the chances of delayed epithelialization and re-perforation in these cases. Administration of topical and systemic immunosuppression, when indicated, helps improve the outcome. This review aims to facilitate clinicians in instituting a synchronized multifaceted therapy for the successful management of corneal perforations in the setting of DED.

Recent advances in diagnosis and management of Mycotic Keratitis.

Mycotic keratitis is a major cause of corneal blindness, especially in tropical and subtropical countries. The prognosis is markedly worse compared to bacterial keratitis. Delayed diagnosis and scarcity of effective antifungal agents are the major factors for poor outcome. Over the last decade, considerable progress has been made to rapidly diagnose cases with mycotic keratitis and increase the efficacy of treatment. This review article discusses the recent advances in diagnosis and management of mycotic keratitis with a brief discussion on rare and emerging organisms. A MEDLINE search was carried out for articles in English language, with the keywords, mycotic keratitis, fungal keratitis, emerging or atypical fungal pathogens in mycotic keratitis, investigations in mycotic keratitis, polymerase chain reaction in mycotic keratitis, confocal microscopy, treatment of mycotic keratitis, newer therapy for mycotic keratitis. All relevant articles were included in this review. Considering the limited studies available on newer diagnostic and therapeutic modalities in mycotic keratitis, case series as well as case reports were also included if felt important.

Acute corneal hydrops in keratoconus.

Acute corneal hydrops is a condition characterized by stromal edema due to leakage of aqueous through a tear in descemet membrane. The patient presents with sudden onset decrease in vision, photophobia, and pain. Corneal thinning and ectasias combined with trivial trauma to the eye mostly by eye rubbing is considered as the underlying cause. With conservative approach self-resolution takes around 2 to 3 months. Surgical intervention is required in cases of non-resolution of corneal edema to avoid complications and for early visual rehabilitation. Intracameral injection of air or gas such as perflouropropane is the most common surgical procedure done. Recent investigative modality such as anterior segment optical coherence tomography is an extremely useful tool for diagnosis, surgical planning, and postoperative follow up. Resolution of hydrops may improve the contact lens tolerance and visual acuity but most cases require keratoplasty for visual rehabilitation.

Ocular allergy and keratoconus.

Keratoconus is the most common corneal ectatic disorder, the cause of which is largely unknown. Many factors have been implicated, and the ocular allergy is being one of them. The commonly proposed pathogenesis includes the release of inflammatory mediators due to eye rubbing which may alter the corneal collagen and lead to corneal ectasias. The onset of keratoconus is often early in cases associated with allergy and routine corneal topography may detect subtle forms of keratoconus. These cases may require early keratoplasty and are at an increased risk of having acute corneal hydrops. Surgical outcomes are similar to primary keratoconus cases. However, post-operative epithelial breakdown may be a problem in these cases. Control of allergy and eye rubbing is the best measure to prevent corneal ectasias in cases of ocular allergy.

Molecular characterization of drug-resistant and drug-sensitive Aspergillus isolates causing infectious keratitis.

Purpose: To study the susceptibilities of Aspergillus species against amphotericin B in infectious keratitis and to find out if drug resistance had any association with the molecular characteristics of the fungi. Materials and Methods: One hundred and sixty Aspergillus isolates from the corneal scrapings of patients with keratitis were tested for susceptibilities to amphotericin B by broth microdilution method. These included Aspergillus flavus (64 isolates), A. fumigatus (43) and A. niger (53). Fungal DNA was extracted by glass bead vertexing technique. Polymerase chain reaction (PCR) assay was standardized and used to amplify the 28S rRNA gene. Single-stranded conformational polymorphism (SSCP) of the PCR product was performed by the standard protocol. Results: Of the 160 isolates, 84 (52.5%) showed low minimum inhibitory concentration (MIC) values (≤ 1.56 μg/ml) and were designated as amphotercin B-sensitive. Similarly, 76 (47.5%) had high MICs (≥ 3.12 μg/ml) and were categorized as amphotericin B-resistant. MIC50 and MIC90 values ranged between 3.12-6.25 μg/ml and 3.12-12.5 μg/ml respectively. A. flavus and A. niger showed higher MIC50 and MIC90 values than A. fumigatus. The SSCP pattern exhibited three extra bands (150 bp, 200 bp and 250 bp each) in addition to the 260 bp amplicon. Strains (lanes 1 and 7) lacking the 150 bp band showed low MIC values (≤ 1.56 μg/ml). Conclusion: A. niger and A. flavus isolates had higher MICs compared to A. fumigatus, suggesting a high index of suspicion for amphotericin B resistance. PCR-SSCP was a good molecular tool to characterize Aspergillus phenotypes in fungal keratitis.

Laser in-situ keratomileusis for refractive error following radial keratotomy.

Aim: To evaluate the safety and efficacy of laser in-situ keratomileusis (LASIK) in eyes with residual/induced refractive error following radial keratotomy (RK). Design: Retrospective study. Materials and Methods: A retrospective analysis of data of 18 eyes of 10 patients, who had undergone LASIK for refractive error following RK, was performed. All the patients had undergone RK in both eyes at least one year before LASIK. Parameters like uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), contrast sensitivity, glare acuity and corneal parameters were evaluated both preoperatively and postoperatively. Statistical Software: STATA-9.0. Results: The mean UCVA before LASIK was 0.16±0.16 which improved to 0.64 ± 0.22 (P < 0.001) after one year following LASIK. Fourteen eyes (out of 18) had UCVA of ≥ 20/30 on Snellen's acuity chart at one year following LASIK. The mean BCVA before LASIK was 0.75 ± 0.18. This improved to 0.87 ± 0.16 at one year following LASIK. The mean spherical refractive error at the time of LASIK and at one year after the procedure was –5.37 ± 4.83 diopters (D) and –0.22 ± 1.45D, respectively. Only three eyes had a residual spherical refractive error of ≥ 1.0D at one year follow-up. In two eyes, we noted opening up of the RK incisions. No eye developed epithelial in-growth till 1 year after LASIK. Conclusion: LASIK is effective in treating refractive error following RK. However, it carries the risk of flap-related complications like opening up of the previously placed RK incisions and splitting of the corneal flap.

Evaluation of retinal nerve fiber layer thickness measurement following laser in situ keratomileusis using scanning laser polarimetry.

AIM: To evaluate the effect of laser-assisted in situ keratomileusis (LASIK) on the measurement of retinal nerve fiber layer thickness by scanning laser polarimetry using customized corneal compensation in myopes. MATERIALS AND METHODS: Scanning laser polarimetry was performed on 54 eyes of 54 healthy patients with myopia using the glaucoma diagnostics variable corneal compensation (GDx VCC) instrument (Laser Diagnostic Technologies, San Diego, California) before and a week after LASIK. The various parameters were compared using the Student's t test. RESULTS: No statistically significant change was observed in any of the retinal nerve fiber layer parameters before and after LASIK. CONCLUSIONS: While the measurement of retinal nerve fiber layer thickness by scanning laser polarimetry is affected by anterior segment birefringent properties and LASIK would be expected to produce changes in the same, customized corneal compensation using the GDx VCC seems to adequately compensate for these changes.

Phenotypic and plasmid pattern analysis of Staphylococcus epidermidis in bacterial keratitis.

BACKGROUND: Staphylococcus epidermidis, a commensal of the conjunctival sac has been incriminated as the commonest etiological agent of bacterial keratitis. However, the pathogenic potential of this commensal organism is not clearly known. AIM: To determine any phenotypic, molecular markers of S. epidermidis pathogenicity in bacterial keratitis. MATERIALS AND METHODS: A total of 382 corneal ulcer isolates of S. epidermidis and 87 S. epidermidis isolates from healthy eyes (controls) were studied. Speciation, biotyping and antibiotic sensitivity testing were performed by conventional methods. Tube slime and adherence tests were carried out by recommended techniques. Plasmid analysis was conducted by a standard protocol. STATISTICAL ANALYSIS: Chi-square test was employed for calculations. RESULTS: Out of 382 corneal ulcer isolates (Pathogens) 284 (74.3%) belonged to biotypes I and II. Slime was detected in 164 (42.9%) of 382 pathogens vs. 21 (24.1%) of 87 controls (P<0.001). Sixty-five (39.6%) of 164 slime positive isolates were multidrug-resistant as compared to only 49 (22.4%) of 218 slime negative isolates (P<0.001). A significantly higher number i.e, 73.1% (120/164) of slime-producers possessed a 21 Kb plasmid in contrast to only 53.2% (116/218) of nonslime-producers (P<0.001). Presence of this plasmid had a statistical correlation of low significance with multidrug resistance (P=0.04). One hundred and seventy-two (45.0%) of 382 pathogens and 24 (27.6%) of the 87 controls were adherent to artificial surfaces (P=0.003) and the majority of the adherent organisms (99/172, 57.6%) were slime producers (P<0.001). CONCLUSIONS: Slime was associated with multidrug resistance in corneal ulcer isolates of S. epidermidis. The 21 Kb plasmid could determine virulence as it was responsible for slime production and adherence.

Recurrent Salzmann's nodular degeneration: report of two cases and review of literature.

Recurrence of Salzmann's nodular degeneration following corneal transplantation is uncommon. The earlier reports of recurrence of Salzmann's degeneration were based on clinical evidence. We report two histopathologically proven cases of recurrence of Salzmann's nodular degeneration following keratoplasty; one recurring after lamellar keratoplasty and the other following penetrating keratoplasty. Two male patients (40 yrs and 24 yrs) presented to us with a clinical picture of Salzmann's nodular degeneration. One patient had undergone lamellar keratoplasty in both eyes for Salzmann's degeneration, 22 years ago. A repeat lamellar keratoplasty was performed in the right eye (7.5 mm/8 mm). In the other patient, penetrating keratoplasty was performed in the left eye, 6 years ago for the same. Lamellar keratoplasty was performed in the left eye (8 mm/8 mm). The histopathologic evaluation of the host button in both the cases, showed features very much suggestive of a recurrence of Salzmann's nodular degeneration.

Need for optical and low vision services for children in schools for the blind in North India.

CONTEXT: Children admitted in blind schools need low vision assessment for improving functional vision (useful residual vision). AIM: To ascertain the need for spectacles and magnifiers as low vision devices (LVD) in children with useful residual vision, attending blind schools. SETTING AND DESIGN: Cross-sectional study conducted in 13 blind schools in Delhi, North India. MATERIALS AND METHODS: Of a total of 703 children (less than 16 years of age) examined, 133 (18.91%) with useful residual vision were refracted and analyzed. High addition plus lenses (range 5-30 diopters) were used as spectacle magnifiers for near LVD assessment. "World health organization (WHO)/ prevention of blindness (PBL) eye examination record for children with blindness and low vision", was used to collect data. SPSS (statistical package for the social science), version 10.0 was used for analysis. RESULTS: Based on the vision of 133 children at initial examination, 70.7% children were blind and 12.0% were severely visually impaired (SVI). 20.3% children improved by at least one WHO category of blindness after refraction. With best correction, 50.4% children were still blind and 13.5% were SVI. Visual acuity in the better eye after refraction in 47 children (35.3%), improved with spectacles. Children with aphakia (17), coloboma (5), refractive error (5) and microphthalmos (4) benefited from spectacles. Of 124 children with low vision but having useful residual vision, 51 (41.1%) were able to read N-10 unaided or with distance spectacles and 30 children (22.6%) improved to N-10 with spectacle magnifiers and were prescribed the same. CONCLUSION: Visually impaired children with aphakia and congenital anomalies of the eye benefit from refraction and low vision services.

In-vivo slit scanning confocal microscopy of normal corneas in Indian eyes.

OBJECTIVE: To study the cellular populations of healthy corneas of Indian eyes using confocal microscopy and to evaluate the correlation with age, gender and laterality. METHODS: The central corneas of 100 eyes of 50 healthy subjects were examined using an in-vivo slit scanning confocal microscope (Confoscan 2). Images were analysed for cell densities of the epithelium, stroma and endothelium. RESULTS: Good quality images enabling analysis of all cell layer populations were obtained in 74 eyes of 43 healthy subjects (22 males and 21 females) with a mean age of 31.89 +/- 13.47 (range 19-71 years). The basal epithelial cell density was 3601.38 +/- 408.19 cells/mm2 (range 3017.3-4231.1 cells/mm2). The mean keratocyte nuclei density in the anterior stroma was 1005.02 +/- 396.86 cells/mm2 (range 571.6-1249.6 cells/mm2) and in the posterior stroma was 654.32 +/- 147.09 cells/mm2 (range 402.6-1049.1 cells/mm2). Posterior keratocyte nuclei density was 30.76% less than the anterior stromal keratocyte nuclei density. The difference in keratocyte nuclei density was statistically significant (P=0.001). The mean endothelial cell density was 2818.1 +/- 361.03 cells/mm2 (range 2118.9-4434 cells/mm2) and the mean endothelial cell area was found to be 385.44 +/- 42.66 mm2 (range 268.9-489.2 mm2). Hexagonal cells formed 22.5-69.4% of the endothelial cell populations (mean 42.04 +/- 11.81%). Mean coefficient of cell size variation was 32.29 +/- 3.06 (range 27.2-39.2). No statistically significant differences were found in cell densities of any corneal layer either between female and male patients or between right and left eyes. Basal epithelial cell density, anterior stromal keratocyte nuclei and posterior stromal keratocyte nuclei density were unaffected by age (r=0.12, 0.07, -0.12 respectively) (P=0.001). There was a statistically significant negative correlation between mean endothelial cell density and increase in age (r=-0.42, P=0.001). Coefficient of cell size variation and age were positively correlated (r=0.73, P=0.001). CONCLUSION: In-vivo slit scanning confocal microscopy is useful for the study of corneal cell populations. Our study provides normative data of these cell populations.

Polymicrobial keratitis in an HIV-positive patient.

We describe a case with non-responding polymicrobial spontaneous corneal ulceration in an HIV-positive patient. Acanthamoeba was among the microorganisms isolated.

Complications of laser-in-situ-keratomileusis.

Laser-in-situ-keratomileusis (LASIK) has become a popular technique of refractive surgery because of lower postoperative discomfort, early visual rehabilitation and decreased postoperative haze. Compared to photorefractive keratectomy (PRK), LASIK involves an additional procedure of creating a corneal flap. This may result in complications related to the flap, interface and underlying stromal bed. The common flap-related complications include thin flap, button holing, free caps, flap dislocation and flap striae. The interface complications of diffuse lamellar keratitis, epithelial ingrowth and microbial keratitis are potentially sight threatening. Compared to PRK, there is less inflammation and faster healing after LASIK, but there is a longer period of sensory denervation leading to the complication of dry eyes. The refractive complications include undercorrection, regression, irregular astigmatism, decentration and visual aberrations. Honest and unbiased reporting is important to understand the aetiology and redefine the management.

Pattern of pediatric ocular trauma in India.

OBJECTIVE: The aim of the study is to identify the causes, demographic and clinical profile and evaluate final visual outcome of pediatric ocular injuries. METHODS: Two hundred and four children aged fourteen years or less presenting to the emergency services of a tertiary care centre with ocular injury were included. Demographic data, nature and cause of injury, duration between injury and presentation to an ophthalmologist and the diagnosis were recorded. Evaluation of visual acuity, anterior segment and fundus were done. All patients were appropriately managed and followed up on days 1, 7, 1 month, 3 and 6 months. RESULT: Majority of injuries occurred in children of 5 years and older (87.7%). There were 133 (65.1%) boys and 71 (34.9%) girls. Forty-nine (24%) cases presented within 6 hours of injury while 70 (34.3%) presented after more than 24 hours after trauma. Most common cause of injury was bow and arrow (15.2%) followed by household appliances(14.3%). Closed globe injuries accounted for 42.2% injuries, open globe for 53.9% and 3.9% were chemical injuries. Best corrected visual acuity of 6/12 or better was achieved in 79 eyes (91.86%) in closed globe group. However, only 17 eyes (15.45%) in open globe group could achieve this. CONCLUSION: Most ocular injuries in children are preventable and occur from unsupervised games like bow and arrow and firecracker, which can lead to significant visual loss.