Evaluating the Effect of Retinal Defocus (Blur) on Lateral Heterophoria

Purpose: This study was conducted to ascertain the effect of retinal defocusing or retinal blur on lateral heterophoria at far and near.Methods: This was a quasi-experimental study involving 57 participants aged 5 to 35 years, who were selected based on the inclusion criteria of being myopes and emmetropes who had a normal general and ocular health. The Von Graefe technique was used for measuring phoria under standard testing conditions.Results: The mean baseline lateral phoria for emmetropes were 0.53 ± 1.14∆ exophoria and 2.47 ± 2.08∆ exophoria at far and near respectively, while after defocusing, it was 2.80 ± 0.88∆ exophoria and 4.34 ± 1.70∆ exophoria at far and near respectively. For myopes, the baseline lateral phoria was 1.52 ± 1.09∆ exophoria and 4.76 ± 1.13∆ exophoria at far and near respectively while after defocussing, it was 3.39 ± 0.92∆ exophoria at far and 7.60 ± 1.00∆ exophoria at near. The mean difference in lateral phoria was found to be significant at the 95% confidence level (P = 0.000). There was no statistically significant difference in lateral phoria change at far (P = 0.072), while the near phoria difference was significant (P = 0.002).Conclusion: Gas Retinal defocusing with +2.50D resulted in a shift towards exophoria at both far and near, with myopes experiencing more exophoric shift. This is because they are less sensitive to the presence of blur. This will enable practitioners to be cautious of the inhibition of accommodation due to higher exophoria at near when prescribing lenses. Keywords: Retinal Defocus, Myopia, Emmetropia, Near lateral phoria, Distance lateral phoria.

Subspecialty training in Ophthalmology; How far?

No Abstract.

Bacterial adhesion to Conventional and Silicone hydrogel contact lenses

Purpose: The aim of this study was to investigate the adhesion of bacteria to worn silicone hydrogel and conventional soft contact lenses.Methods: Bacterial adhesion experiments / assays were performed on 24 worn and 6 unworn soft contact lenses each of different materials (high- and low- gas permeable lenses) using the strains such as Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 25923.Results: P. aeruginosa adhered in increased number to worn than unworn Lotrafilcon A and conventional lenses. However, a higher number of P. aeruginosa adhered to unworn than worn Lotrafilcon B, the difference in the mean adhesion was not significant (p = 0.66). S. aureus adhered in significantly decreased number to worn Lotrafilcon A, nelfilcon A, nesofilcon A, etafilcon A and omafilcon A (p<0.05); butsignificantly higher number adhered to worn than unworn polymacon (p<0.05). Lens wear had no effect on the adhesion of S. aureus to Lotrafilcon B (p>0.05). The least adhesion of P. aeruginosa to worn contact lenses was seen with polymacon, while S. aureus adhered in least number to worn Lotrafilcon A compared to the other contact lens materials that demonstrated the same trend in adhesion.Conclusion: The higher adhesion of P. aeruginosa to worn lenses is consistent with the claim that it is the most implicated in all culture-positive contact lens related bacterial keratitis. Lens wear has different effects on bacterial adhesion, which may be due to type of lens materials and bacterial species/genera studied. Keywords: Silicone hydrogel lenses, conventional lenses, Pseudomonas aeruginosa, Staphylococcus aureus, bacterial adhesion.

Assessment of Dry Eye Syndrome among Computer Programmers in Computer Training Institutes in Benin City

Purpose: The purpose of this study was to evaluate dry eye syndrome among computer programmers in computer training institutes in Benin City.Methods: This cross-sectional study was carried out using 250 participants of 18 years and above who were computer instructors and students of various computer training institutes in Benin City. Sociodemographic data and relevant ocular history were obtained from the participants. External and Internal examinations of the eyes were carried out to check for the presence of any ocular abnormalities. Dryeye disease was assessed subjectively with the Ocular Surface Disease Index (OSDI) questionnaire and objectively by performing Schirmer’s test and Tear Break-up Time (TBUT). Participants with an OSDI score of ≥35 and who had < 10mm to Schirmer’s I test or < 10secs in Tear break-up Time (TBUT) test were considered to have dry eye.Results: The mean age of the participants was 25.32 ± 7.38 years and 68% were males. The prevalence of dry eye among the computer programmers was found to be 30.8%. Mean TBUT and Mean Schirmer’s Test value for those with dry eye was 10.21s±3.44s and 12.46 ± 7.27mm respectively. This study showed that age (p=0.213), gender (p=0.243) and duration of time spent on computer display units (p=0.124) were not statistically significant determinants of dry eye among the computer programmers.Conclusion: Computer programmers are predisposed to developing dry eye diseases. It is therefore imperative for them to go for regular eye examination to prevent ocular surface disorders and therefore maintain comfortable vision. Keywords: Dry Eye, Schirmer Test, Tear Break-up Time, Ocular Surface Disease Index, Computer Programmer.

Photostress Recovery Time Among Welders in Owerri Municipal Council, Southeast, Nigeria

Purpose: The photostress recovery time (PSRT) scores of welders were measured based on age, workexperience and welding-method.Methods: A quasi-experimental study was conducted among 50 purposively sampled welders, who had clear ocular media, healthy fundi and visual acuities of 6/6 or better in the tested eyes. The pre-bleach distant visual acuity of the right eye was determined with the Snellen’s visual acuity chart, while direct ophthalmoscopy was done to rule out media opacities, retinopathies and maculopathies. The right eye was dazzled for 10 seconds with the light of a direct ophthalmoscope held at 2cm from the eye. The time required in seconds to read at least, three optotypes on the line directly above the baseline acuity was recorded as the PSRT.Results: The 22-31 years age group recorded the least mean PSRT (16±8.8seconds), followed by the 32-41 age group (19.9±6.8 seconds), while the 42-51 years category had the highest mean PSRT (31.4±10.5seconds). Age associated significantly (p˂0.05) with mean PSRT. Welders within the 1-12 years’ work experience had the least mean PSRT (15.9±8.1seconds) while those within the 25-36 years recorded the highest mean PSRT (33.4±9.3seconds). The observed difference in mean PSRT with years of work experience was statistically significant (p˂0.05). Gas welders had significantly (p˂0.05) higher mean PSRT (26.6±9.9secs) than electric arc welders (16.6±9.2secs).Conclusion: Gas welding, increasing age and work-experience were found to be predictive markers of elevated photostress recovery time (PSRT) among welders. This underscores the need for eye-care practitioners to routinize PSRT tests in the ocular assessment of welders. Keywords: Photostress recovery time (PSRT); electric-arc; gas welding; welders; age.

Editorial - Covid-19: A Global Challenge – Misinformation, Misconceptions And Myths

No Abstract.

Editor’s notes

No Abstract.

Spectral Transmission of Porcine Crystalline Lens at Post-Mortem Interval

Purpose: Determining the total spectral transmission of the porcine crystalline lens at various post mortem intervals. Method: An experimental study conducted in the Department of chemical Pharmacology, Faculty of pharmacy, University of Benin. Twenty pairs of porcine eyes were obtained from an abattoir in Benin City. The crystalline lenses were carefully extracted from the enucleated porcine eyes at various post- mortem intervals (0, 12, 24, 36 and 48hours) and their spectral transmissions were measured using a T80 UV-VIS Spectrophotometer. Measurement at 0 hour was used as a control being the baseline. Result: The result showed a strong negative correlation between increased post mortem intervals and transmission of the crystalline lens for both eyes, as the post-mortem time interval increases, the transmission of long wavelengths (r = -0.992, P = 0.001), mid wavelengths (r = -0.994, P = 0.000) and short wavelengths(r = -0.991, P = 0.001) decreases significantly. It was also observed there was no significant difference (P> 0.05) existed between both eyes in the different wavelength regions with increased post mortem interval. Conclusion: The study shows that time after death has effect on the spectral transmission of crystalline lens which can serve as important information in forensic evaluation. Key words: Post mortem interval, crystalline lens, spectral transmission, spectrophotometer and porcine.

Editor’s notes

No Abstract.

Accommodative-Convergence Mechanism failure in HIV-Positive Non Presbyopic Patient on Highly Active Anti-Retroviral Therapy: A case report

Purpose: Accommodative-convergence mechanism failure could occur in non presbyopic HIV- sero positive patients on Highly Active Anti-Retroviral Therapy (HAART). This could be due to either direct neuronal infection by HIV, pathologic changes of the lens or the ciliary body or adverse effects of some individual drugs constituting the HAART regimen on the cranial nerves which play vital roles in the mechanism of accommodation and convergence. Case report: This is a case report of an accommodative- convergence mechanism failure in HIV positive non presbyopic 32-year-old male patient that was on HAART for more than five years. He presented with distance visual acuity (VA) of OD: 6/9 +2, OS: 6/9, and near visual acuity (NVA) of N24 both eyes, 3Δ esophoria at distance and 4Δ esophoria at near. Amplitude of accommodation (AA) was 3.50D and accommodative convergence/accommodation (AC/A) ratio was 6/1. Following comprehensive evaluation, his refractive correction was OD: Plano/-0.50DC X 180 6/5 and OS: Plano/-0.50DC X 90 6/5 at distance with near addition (Add) 2.50D N5. This was prescribed for regular wear in form of D-Top bifocal lens. Conclusion: These findings showed that HIV sero-positive adults on HAART could develop accommodativeconvergence mechanism failure, which may be characterized by low amplitude of accommodation, receded near point of convergence and high non presbyopic reading addition. These conditions may be under-recognized and need for reading addition of a non presbyopic age is often overlooked. Key Words: Accommodative-Convergence, HIV, Lateral Phoria, Refractive error.