Parthasarathi Roy

Abstract

Aims: To establish normative database and investigate whether VEP amplitude and latency have any correlation between them. Methods: Institution based cross-sectional observational study done in Electrophysiology of Vision Laboratory at a tertiary centre in Eastern India. 126 subjects of age group between 20 and 59 years of either sex with best corrected visual acuity 6/6 in both eyes and no other eye ailments (except error of refraction) on examination with informed consent were included. PVEP with pattern reversal stimulus with check element size 1° (60') was recorded with Retimax “Advanced” machine (manufactured by CSO s.r.l., (Firenze) Italy) and standard silver-silver chloride disc electrodes. The test parameters were customized in the machine by the manufacturer and designated to measure the N75-P100 amplitude and P100 latency. Results: Normative values were established for our laboratory. Only the most reliable parameters for clinically significant alterations of visual pathway i.e. N75-P100 amplitude and P100 latency were included in the analysis. Results of uniocular, age group-wise, and gender-wise values were obtained by descriptive statistics as per ISCEV guidelines. No linear co-relationship (ascertained by Spearman's rho Correlation Coefficient) was found between N75-P100 amplitude and P100 latency, in either of the eyes. Conclusions: PVEP amplitude and latency are uncorrelated variables. To the best of our knowledge, our study was the first study in the literature on correlation between the amplitude and latency of PVEP.   Keywords: Pattern visual evoked potential, N75-P100 amplitude, P100 latency, Correlation

Open full article page

Abstract

Acanthamoeba keratitis is diagnosed fairly late because of lack of early clinical suspicion and unavailability of simple and effective technique for detection of the protozoa in ordinary laboratory settings. The detection of motile trophozoites in wet mount preparation of corneal scraping is probably the best confirmatory test of Acanthamoeba keratitis in ordinary laboratory settings. However, it is not easy to demonstrate motile trophozoites given the fact that the trophozoites rapidly encyst outside living tissue. We employed a protocol of preparation and transport of the wet mount to the nearby laboratory within fifteen minutes whereby optimum chance of demonstration of motile trophozoites was possible. We had been successful to detect the typical amoeboid movement of acanthamoeba in three cases. Healing of ulcers were achieved by an appropriate therapy in all three cases. Visual recovery was good in two out of three cases. To the best of our knowledge, the present case series is the first one in English literature where diagnosis of acanthamoeba keratitis is based solely on detection of motile trophozoites in direct wet mount examination. Key Messages: A careful history and an incisive look into the corneal lesion revealed some clue to suspect the acanthamoeba etiology. Simple laboratory technic employing wet mount microscopy rapidly confirmed the diagnoses. Healing of ulcers were achieved in all three cases by instillation of 0.02% chlorhexidine eye drop. Visual recovery was good in two out of three cases.   Keywords: Acanthamoeba keratitis, Wet mount microscopy, Motile trophozoites.

Open full article page

Abstract

Background:  Conventionally adrenergic-anticholinergic combination eye drops (e.g., phenylephrine-tropicamide) are used for pre-operative pupillary dilatation in cataract surgery. This achieves synergy in dilatation, but anticholinergic-induced cycloplegia makes already tense lens-capsule of intumescent cataract more taut, and completion of capsulorrhexis becomes difficult, often resulting in Argentanian flag sign, peripheral extension. An alternative mydriasis-without-cycloplegia strategy (phenylephrine) is also tried for better maintenance of mydriasis but it’s capsule-slackening effect was not thought of. Making best of both, we practice a ‘minimal-cycloplegia mydriasis’ approach (MCM) comprising of 0.25% tropicamide and 5% phenylephrine, instilled in succession. This study was planned to compare our MCM regimen with the conventional fixed-dose-combination regimen of 0.8% tropicamide and 5% phenylephrine (Standard). Objectives:  To compare the ease and smoothness of capsulorrhexis and relative incidence of complications, in hypermature intumescent cataract surgery, between ocular instillation of alternative ‘MCM’ regimen and the traditional ‘Standard’ regimen. Materials and Methods:  The study used a prospective observational 2-arm comparison design. The study commenced with due approval of Institutional Ethics Committee. Sixty-one (61) patients (age range: 42-72yrs, number of Male: Female 19:42) undergoing hypermature intumescent cataract surgery by standard SICS+IOL technique and in whom either of two regimens, MCM or ‘Standard’ were used for papillary dilatation, were observed. Outcome analysis was done by Fisher’s Exact Test. Results:  Out of a total of 61 cases, 29 received MCM regime and 32 received ‘Standard’ cycloplegic dilator. Difference in dilatation between two groups was statistically non-significant. Frequency of completed rhexis and attainment of post-operative BCVA of 6/12 were higher with MCM regime: p< 0> Conclusion:  Minimal-cycloplegia dilatation regime comprising of 0.25% tropicamide and 5% phenylephrine, instilled in succession may be preferred for capsulorrhexis in hypermature intumescent cataract.   Keywords: Mydriasis, Phenylephrine, Capsulorrhexis in hypermature.

Open full article page