Corneal epithelial permeability to fluorescein in humans by a multi-drop method.

PURPOSE: The permeability of the corneal epithelium to fluorescein Pdc is an indicator of the health of the ocular surface. It can be measured in a clinical setting by determining the accumulation of fluorescein in the stroma following administration of the dye on the ocular surface. Here we demonstrate a new multi-drop method for the measurement of Pdc by a spot fluorometer. METHODS: Twenty-nine healthy participants were recruited for this study. First, a probe-drop of fluorescein (0.35%, 2 µL) was instilled on the conjunctiva. The clearance of the dye from the tears was immediately measured using the fluorometer. Following this, two loading drops (2%; 6 µL each) were administered 10 min apart. Fifteen minutes later, the ocular surface was washed and fluorescence from the stroma Fs was measured. Permeability was calculated using Pdc = (Q x Fs)/ (2 x AUC), where Q is the stromal thickness and AUC is the area under the fluorescence vs. time curve for the loading drops. RESULTS: After the probe drop, the tear fluorescence followed an exponential decay (elimination rate constant; kd = 0.41 ± 0.28 per min; 49 eyes of 29 subjects), but the increase in Fs was negligible. However, after the loading drops, the measured Fs was ~ 20-fold higher than the autofluorescence and could be recorded at a high signal to noise ratio (SNR > 40). The intra-subject variability of kd was insignificant. Since fluorescein undergoes concentration quenching at > 0.5%, the value of AUC for the loading drops was estimated by scaling the AUC of the probe drop. The calculated Pdc was 0.54 ± 0.54 nm/sec (n = 49). A Monte Carlo simulation of the model for the multi-drop protocol confirmed the robustness of the estimated Pdc. CONCLUSIONS: The new multi-drop method can be used in place of the single-drop approach. It can overcome a lack of sensitivity in fluorometers of high axial resolution. The Pdc estimated by the multi-drop method is ~ 11-fold higher than previously reported but closer to the value reported for other drugs with equivalent octanol/water partition coefficient.

Keratoprosthesis: Current global scenario and a broad Indian perspective.

Keratoprosthesis (Kpro) forms the last resort for bilateral end-stage corneal blindness. The Boston Type 1 and 2 Kpros, the modified osteo-odonto Kpro and the osteo-Kpro are the more frequently and commonly performed Kpros, and this review attempts to compile the current data available on these Kpros worldwide from large single-center studies and compare the indications and outcomes with Kpros in the Indian scenario. Although the indications have significantly expanded over the years and the complications have reduced with modifications in design and postoperative regimen, these are procedures that require an exclusive setup, and a commitment toward long-term follow-up and post-Kpro care. The last decade has seen a surge in the number of Kpro procedures performed worldwide as well as in India. There is a growing need in our country among ophthalmologists to be aware of the indications for Kpro to facilitate appropriate referral as well as of the procedure to enable basic evaluation during follow-ups in case the need arises, and among corneal specialists interested to pursue the field of Kpros in understanding the nuances of these surgeries and to make a judicious decision regarding patient and Kpro selection and more importantly deferral.

Factors affecting treatment outcome in congenital nasolacrimal duct obstruction: A retrospective analysis from South India.

PURPOSE: To investigate outcomes for different treatment modalities in congenital nasolacrimal duct obstruction (CNLDO) in an Indian population. DESIGN: Retrospective, interventional, case series. MATERIALS AND METHODS: In an institutional setting, case records of patients with CNLDO from January 2008 to 2012, were reviewed, and data on patient demographics, clinical presentation, and treatment details (sac massage, probing, and/or dacryocystorhinostomy) were recorded. Success of treatment was defined as complete resolution of symptoms and negative regurgitation on pressure over lacrimal sac (ROPLAS) area. RESULTS: Two hundred and ninety-eight eyes of 240 patients with a mean age of 22.2 ± 26.14 months (median = 12 months, interquartile range = 17) were analyzed. Sac massage (n = 226) was successful in 67 eyes (30%). Multivariable logistic regression analyses showed that children with mucoid ROPLAS were almost 6 times more likely (odds ratio [OR] = 5.55 vs. clear ROPLAS, 95% confidence interval [CI] = 2.35-13.09, P < 0.001) to experience failure of sac massage. Overall probing (n = 193) was successful for 143 (74%) eyes. Multivariable logistic regression showed that older children were 25% more likely to experience probing failure (OR = 1.25 for every 6 months increment in age, 95%, CI = 1.09-1.42, P = 0.001). CONCLUSION: Sac massage is successful in only a third of our patients and those with mucoid ROPLAS are more likely to experience failure. Probing is successful in three-quarter of our subjects, and its success declines with a progressive increase in age. Lower socioeconomic status, poor general health, and recurrent respiratory infections are unique to our population and may influence outcomes.