Comparison of the clinical estimation of cup-to-disk ratio by direct ophthalmoscopy and optical coherence tomography.

OBJECTIVE: To compare the clinical estimation of cup-to-disk ratio determined by direct ophthalmoscopy and optical coherence tomography in glaucoma diagnosis and monitoring. METHODS: A retrospective, cross-sectional study involving a review of 71 optical coherence tomography scans dating from June 2011 to January 2012 at a private imaging lab in Ghana. At the respective referring facilities, only 31 out of the 71 corresponding patient records were successfully reviewed. RESULTS: Majority (54.84%) of the 31 patient records successfully reviewed were women. The mean age was 44.54 ± 16.15 years. Cup-to-disk ratio was grouped into ⩽0.4, >0.4-0.6, >0.6-0.8, and >0.8-1.0 based on direct ophthalmoscopy values. The overall mean cup-to-disk ratio estimated by the optical coherence tomography and direct ophthalmoscopy were 0.72 ± 0.21 and 0.60 ± 0.26, respectively. Overall, there was no statistically significant difference in the mean cup-to-disk ratio estimation by direct ophthalmoscopy and optical coherence tomography [right eye (p = 0.0629); left eye (p = 0.0766)]. There was a statistically significant difference between direct ophthalmoscopy and optical coherence tomography cup-to-disk ratio estimation for values ⩽0.4 [right eye (p = 0.0061); left eye (p = 0.0063)] and values >0.4-0.6 [right eye (p = 0.0243); left eye (p = 0.0498)]. There was no statistically significant difference between conventional direct ophthalmoscopy and optical coherence tomography cup-to-disk ratio estimation for cup-to-disk ratio >0.6. CONCLUSION: We recommend clinicians document which method they use in evaluating optic nerve head parameters. This is to ensure that subsequent clinical decisions are not influenced by an apparent change in these parameters, especially cup-to-disk ratio as different methods might give different values.

Relationship between Reduced Accommodative Lag and Myopia Progression.

PURPOSE: To determine the relationship between accommodative lag and rate of myopia progression when Ghanaian myopic school children are either undercorrected or fully corrected with single vision lenses. METHODS: A 2-year single masked randomized control trial was conducted using 150 Ghanaian myopic children aged 10 to 15 years with mean baseline myopia of -1.98 ± 0.50D. The children were randomly assigned to wear either a full correction (n = 75) or +0.50D undercorrection (UC) (n = 75) single vision lenses. Repeated measurements which included refractive error and accommodative response at 33 and 28.6 cm for FC and UC, respectively, were performed using Open-Field Autorefractor whereas ocular biometry results were obtained using A-Scan ultrasonography. Results were based on the right eye and analyzed using STATA 11. RESULTS: After 24 months, the mean myopia progression of children in the FC group (-0.54 ± 0.26D) was not significantly different from that of the children in the UC group (-0.5 ± 0.22D) (p = 0.31). There was no significant difference between the mean values of the initial near lag and the average lag measured 24 months later in both groups (FC: initial lag -0.74 ± 0.17D, average lag -0.72 ± 0.15D, p = 0.44; UC: initial lag -0.57 ± 0.14D, average lag -0.58 ± 0.15D; p = 0.67). Also, there was no significant correlation between refractive change seen in 24 months and either the first near lag for both FC (r = -0.05, p = 0.43) and UC (r = -0.08, p = 0.43) or the average near lag of accommodation for both FC (r = -0.02, p = 0.49) and UC (r = -0.04, p = 0.49). CONCLUSIONS: This study showed no relationship between lag of accommodation and rate of myopia progression in children with progressing myopia. Different ethnic groups may respond differently to the same size of hyperopic blur.

Assessment of corneal astigmatism following frown and straight incision forms in sutureless manual small incision cataract surgery.

To investigate which of two tunnel incision forms (frown versus straight) in sutureless manual small incision cataract surgery creates more corneal astigmatism. Sixty eyes of 60 patients who had consented to undergo cataract surgery and to partake in this study were followed from baseline through >12-week postoperative period. Values of preoperative and postoperative corneal astigmatism for the 60 eyes, measured with a Bausch and Lomb keratometer, were extracted from the patients' cataract surgery records. Residual astigmatism was computed as the difference between preoperative and postoperative keratometry readings. Visual acuity was assessed during the preoperative period and at each postoperative visit with a Snellen chart at 6 m. Fifty eyes of 50 patients were successfully followed-up on. Overall, the mean residual astigmatism was 0.75±0.12 diopters. The differences in mean residual astigmatism between the two different incision groups were statistically significant (t [48]=6.33, P<0.05); frown incision group recorded 1.00±0.12 diopters, whereas the straight incision group recorded 0.50±0.12 diopters. No significant difference was observed between male and female groups (t [48]=0.24, P>0.05). Residual corneal astigmatism in the frown incision group was significantly higher than in the straight incision group. Fisher's exact test did not reveal a significant association between incision forms and visual acuity during the entire postoperative period (P>0.05).