Smartphone usage among people living with severe visual impairment and blindness.

Low vision care and rehabilitation is often limited by access to assistive devices, especially in low-resourced countries, due to their high cost and unavailability. Smartphones have the potential to serve as an alternative assistive device for people living with severe visual impairment and blindness (SVIB). This study aims to investigate the use of smartphones among people living with SVIB. The study was a cross-sectional study of 166 people living with SVIB in a low resourced setting. The participants were recruited from two tertiary institutions and four eye care facilities. A questionnaire was administered to all respondents and for those who could not read prints they were read out to them and their responses recorded. The majority of respondents (n = 88, 53.1%) either had no phone or used a basic phone. The prevalence of smartphone usage among people living with SVIB was found to be 46.90% (n = 78). Most respondents use their smartphones to interact on social media [n = 75 (96%)] and web browsing [n = 69,92%]. The most frequently demanded [n = 22 (44%)] smartphone functionality by the respondents was the image and color description feature. Most participants were unaware that 90% of their functionality demands already existed and were compatible with current smartphones. A significant number of people living with SVIB in this study used smartphones; however, most users are unaware of its full functionality and assistive capabilities.

Convergence insufficiency symptom survey (CISS) scores are predictive of severity and number of clinical signs of convergence insufficiency in young adult Africans.

PURPOSE: This study aimed to investigate the correlation between convergence insufficiency symptom survey (CISS) score and the signs of convergence insufficiency (CI) and to evaluate the sensitivity and specificity of the CISS to predict CI and ametropia among young adult university students. METHOD: This prospective cross-sectional clinic-based study included 300 first year university students (mean age = 21.58 (SD ± 2.2) years) who consecutively reported for eye examination. Participants were administered the CISS questionnaire and investigated for the signs of CI. Diagnosis of CI was based on presence of three or four signs. The correlation between the CISS score and the signs of CI were determined and Receiver Operation Characteristics (ROC) curves were used to evaluate sensitivity and specificity. RESULTS: There were significant correlations between CISS score and the clinical signs of CI namely NPC break (rs = 0.622, p = 0.0001), NPC recovery (rs = 0.620, p = 0.0001), near exophoria (rs = 0.434, p = 0.0001), near PFV blur (rs = -0.359, p = 0.0001), near PFV break (-0.306, p = 0.0001), near PFV recovery (rs = -0.326, p = 0.0001) and gradient AC/A ratio (rs = -0.290, p = 0.0001). There was a significant positive correlation between CISS score and the number of clinical signs of CI (rs = 0.575, p-value = 0.0001). The CISS had good sensitivity (AOC = 0.882) to predict CI and poor sensitivity (AOC = 0.642) to predict ametropia. CONCLUSION: The CISS score is correlated with the severity and number of signs of CI in young adult Ghanaian university students. Its use in addition to clinical investigative testing may give a definitive diagnosis of symptomatic CI.

Disability glare and nighttime driving performance among commercial drivers in Ghana.

OBJECTIVE: Glare caused by the headlights of on-coming vehicles risk safe driving at night. The study aimed to determine the relationship between glare exposure and nighttime driving performance among commercial drivers in Ghana. METHODS: This cross-sectional study involved commercial drivers with complaints of nighttime driving difficulties (N = 80; mean age = 41.5 ± 11.1 years). A questionnaire was used to investigate nighttime driving performance following glare exposure. We measured contrast sensitivity and visual acuity under photopic conditions. With an experimental setup in a mesopic setting, we measured visual acuity with and without glare exposure. The difference between the two mesopic visual acuities was quantified as disability glare index. With the same setup, photostress recovery time was also measured. Regression analyses were used to determine the relationship between nighttime driving performance score and the measures taken in both photopic and mesopic settings. RESULTS: The average nighttime driving performance score was 47.8 ± 17.5. Driving performance was negatively correlated with all variables (R = -0.87 to -0.30, all p < .01), except contrast sensitivity (R = 0.74, p < .01). A multiple linear regression showed that the model with all variables explained 83.8% of the variance, but only disability glare index was a significant predictor of nighttime driving performance following glare exposure (standardized B = -0.61, p < .01). CONCLUSION: Our results show that the change in mesopic visual acuities following glare can predict nighttime driving performance. This measure can be incorporated into the assessment of driving fitness by licensing departments to evaluate whether a person can drive safely at night amidst glare exposure.

Normative Values of Retinal Nerve Fibre Layer Thickness and Optic Nerve Head Parameters and Their Association with Visual Function in an African Population.

PURPOSE: To determine normative values of retinal nerve fibre layer thickness (RNFL) and optic nerve head (ONH) parameters and their association with routine clinical tests such as refractive error (RE), stereoacuity (SA), and contrast sensitivity (CS) in an African population. METHODS: In a cross-sectional observational study, 100 normal subjects aged 20 to 78 years were evaluated using the Cirrus HD-OCT 5000 and matched with 200 glaucoma patients. RESULTS: Average (±SD) RNFL thickness for normal subjects was found to be 102.37 ± 7.45 (range, 82-119 microns) compared with 90.74 ± 14.50 found for glaucoma subjects. Females had higher average RNFL values (104.84 ± 6.90) compared with males (99.80 ± 7.18). Significant associations were calculated between quadrant RNFL thickness and SA, SE, and CS (all p < 0.05). The mean cup to disc ratio (CDR) was 0.49 ± 0.12, and mean optic disc area (DA) was 2.08 mm2 ± 0.40. Smaller DA was recorded for participants aged 60+ years (1.86 ± 0.25), followed by 40-59 age group (2.01 ± 0.41) and then 20-39 age group (2.19 ± 0.41). Significant associations were calculated between SA and ONH parameters, except rim area (all p < 0.05). The mean cup to disc ratio (CDR) was 0.49 ± 0.12, and mean optic disc area (DA) was 2.08 mm2 ± 0.40. Smaller DA was recorded for participants aged 60+ years (1.86 ± 0.25), followed by 40-59 age group (2.01 ± 0.41) and then 20-39 age group (2.19 ± 0.41). Significant associations were calculated between SA and ONH parameters, except rim area (all p < 0.05). The mean cup to disc ratio (CDR) was 0.49 ± 0.12, and mean optic disc area (DA) was 2.08 mm2 ± 0.40. Smaller DA was recorded for participants aged 60+ years (1.86 ± 0.25), followed by 40-59 age group (2.01 ± 0.41) and then 20-39 age group (2.19 ± 0.41). Significant associations were calculated between SA and ONH parameters, except rim area (all. CONCLUSION: RNFL thickness in healthy black Ghanaian population was significantly higher than that reported in other races. The values and associations reported in this study can inform clinical decision on the normal variation in RNFL and optic disc parameters.

Assessing the Progress towards Achieving "VISION 2020: The Right to Sight" Initiative in Ghana.

Purpose: The aim of this study was to analyse eye health delivery in Ghana and examine the progress towards achieving VISION 2020 indicator targets. Methods: This descriptive cross-sectional study was conducted between October 2017 and May 2018. It used a mixed method approach including desk-based reviews, a questionnaire-based survey of eye facilities in Ghana, and interviews with eye health system stakeholders to collect information on eye health delivery in facilities owned by the Ghana Health Service (GHS), quasigovernmental bodies (security agencies), and Christian Association of Ghana (CHAG). The information was benchmarked against the World Health Organization (WHO) targets for achieving the goals of VISION 2020. Results: The magnitude of blindness and moderate to severe visual impairment (without pinhole) was 0.9% and 3.0%, respectively. The number of ophthalmologists available at the country level was 80.6% of the VISION 2020 target with optometrists and ophthalmic nurses exceeding targets for VISION 2020. The distribution of human resources was heavily skewed towards two out of the 10 regions in Ghana. Cataract surgical rate was low and met 25% of the WHO target. Basic equipment for refraction was available in the majority of facilities; however, there was a general lack of specialised eye care equipment across the country. Comparatively, CHAG facilities were better equipped than GHS facilities at the same level. Conclusion: The Government of Ghana should revitalize the goals of VISION 2020 beyond the year 2020 and spearhead a concerted effort to ensure equitable distribution of human and infrastructural resources across the country.

The Relationship Between the Photopic Negative Response and Retinal Ganglion Cell Topography.

Purpose: To assess the topographic relationship between the photopic negative response (PhNR) and retinal ganglion cell distribution in healthy individuals. Method: Data was recorded from 16 healthy participants. The amplitude of PhNRs obtained in response to focal long duration (250 ms) and brief flash (5 ms), red (660 nm) on blue (469 nm) stimuli of increasing size (5° - full field) were measured. The number of retinal ganglion cell receptive fields (RGCf) in each stimulus area was established from the literature and regression analysis used to determine the relationships between: PhNR amplitude and number of RGCfs stimulated, PhNR density and the RGCf density and response per RGCf as a function of eccentricity. Results: The overall amplitude of the PhNR increased with stimulus size and the response density declined from ∼0.1 µV/deg in the macular region to ∼0.003 µV/deg approximately 45° from the fovea. Contrary to expectations, the relationship between the PhNR and number of RGCf was nonlinear, the response from more eccentric neurons being about three times greater than those in the macular region. Conclusions: Although the amplitude of the PhNR broadly maps on to the topographic distribution of RGCf the increase in PhNR amplitude with increasing eccentricity is only partly explained by RGCf numbers. Increases in the PhNR amplitude may be due to topographic variations in the contributions from other non-RGC neurons, as well as eccentricity-related morphologic and physiologic differences in RGCs.

Electrophysiological ON and OFF Responses in Autosomal Dominant Optic Atrophy.

PURPOSE: To assess the effect of autosomal dominant optic atrophy (ADOA) on ON and OFF retinal ganglion cell (RGC) function by evaluating the ON and OFF components of the photopic negative response (PhNR). METHODS: Twelve participants from six families with OPA1 ADOA and 16 age-matched controls were recruited. Electrophysiological assessment involved pattern ERGs (PERGs), focal (20°) and full-field long-duration (250 ms) flash ERGs using a red light-emitting diode flash on a rod-saturating blue background, and full-field brief (300 µs) xenon flash ERGs using a red filter over a continuous rod saturating blue background. Amplitudes and implicit times of the ERG components were analyzed and the diagnostic potential of each electrophysiological technique was determined by generating receiver operating characteristic (ROC) curves. RESULTS: Mean amplitudes of the N95 and all PhNRs, except the full-field PhNRON, were significantly reduced in participants with ADOA (P < 0.01). Subtraction of the group-averaged focal ERG of ADOA participants from that of controls showed an equal loss in the focal PhNRON and PhNROFF components, whereas in the full-field ERG the loss in the PhNROFF was greater than that in the PhNRON component. The areas under the ROC curve (AUC) for the focal PhNRON (0.92), focal PhNROFF (0.95), and full-field PhNROFF (0.83), were not significantly different from that of the PERG N95 (0.99). CONCLUSIONS: In patients with ADOA, the PhNRON and PhNROFF components are nearly symmetrically reduced in the long-duration ERG, suggesting that ON- and OFF-RGC pathways may be equally affected.