Prevalence of visual problems in a rural population of Kenya

Prevalence of visual impairment and refractive errors in an urban area of Mexico

AIM

To determine the distribution of refractive errors in a school-age population in Quintana Roo (Mexico) in the framework of an international cooperation campaign for the prevention of blindness.

METHODS

A sample of 2647 school-age children (ranging from 5 to 14 years old) with a mean age of 9.1±1.9 years old were tested by trained volunteers for distance visual acuity (VA) and refractive errors. The first screening examination included uncorrected distance visual acuity (UDVA) and VA with a +2.00 D lens. Inclusion criteria for a second complete cycloplegic eye examination performed by an optometrist were UDVA <20/25 (0.10 logMAR or 0.8 decimal) and/or VA with +2.00 D ≥20/25.

RESULTS

A total of 633 (23.9%) children underwent the second complete eye examination. Mean logMAR UDVA was 0.035±0.094 (range 1.00 to 0.00 logMAR) for the right eyes and 0.036±0.160 (range 1.00 to 0.00 logMAR) for the left eyes. Bilateral amblyopia was found in 17 children (2.7% of refracted eyes; 0.64% of the total). The main reason for visual impairment (VI) in the sample analyzed was found to be refractive errors. In 12 children (1.9% of refracted eyes; 0.45% of the total) the VI was bilateral and 9 (1.4% of refracted eyes; 0.34% of the total) achieved a corrected distance visual acuity of 20/25 or better in both eyes. Mean magnitude of sphere and refractive cylinder was +0.20±0.96 D and -0.43±0.85 D in right eyes, and +0.24±1.08 and -0.43±0.83 D in left eyes. The proportion of myopic eyes [standard equivalent (SE) ≤-0.50 D] was 4.6% of the whole sample (5290 eyes). The mean magnitude of myopia was -0.84±3.44 D for the right eyes and -0.82±5.21 D for the left eyes. The proportion of hyperopic patients (SE≥+2.00 D) was 2.4% (15/633), which corresponded to 0.60% of the whole sample (32/5290 eyes). No statistically significant correlation of age to manifest sphere or cylinder was found.

CONCLUSION

VI due to uncorrected refractive errors can be easily corrected with glasses but it is still a burden to be treated. Myopia is prevalent in this sample. More efforts towards correcting uncorrected refractive errors are needed.

Refractive error study in young subjects: results from a rural area in Paraguay

AIM

To evaluate the distribution of refractive error in young subjects in a rural area of Paraguay in the context of an international cooperation campaign for the prevention of blindness.

METHODS

A sample of 1466 young subjects (ranging from 3 to 22 years old), with a mean age of 11.21±3.63 years old, were examined to assess their distance visual acuity (VA) and refractive error. The first screening examination performed by trained volunteers, included visual acuity testing, autokeratometry and non-cycloplegic autorefraction. Inclusion criteria for a second complete cycloplegic eye examination by an optometrist were VA <20/25 (0.10 logMAR or 0.8 decimal) and/or corneal astigmatism ≥1.50 D.

RESULTS

An uncorrected distance VA of 0 logMAR (1.0 decimal) was found in 89.2% of children. VA <20/25 and/or corneal astigmatism ≥1.50 D was found in 3.9% of children (n=57), with a prevalence of hyperopia of 5.2% (0.2% of the total) in this specific group. Furthermore, myopia (spherical equivalent ≤-0.5 D) was found in 37.7% of the refracted children (0.5% of the total). The prevalence of refractive astigmatism (cylinder ≤-1.50 D) was 15.8% (0.6% of the total). Visual impairment (VI) (0.05≤VA≤0.3) was found in 12/114 (0.4%) of the refracted eyes. Main causes for VI were refractive error (58%), retinal problems (17%, 2/12), albinism (17%, 2/12) and unknown (8%, 1/12).

CONCLUSION

A low prevalence of refractive error has been found in this rural area of Paraguay, with higher prevalence of myopia than of hyperopia.

Safety and Efficacy of the Transition from Extracapsular Cataract Extraction to Manual Small Incision Cataract Surgery in Prevention of Blindness Campaigns

PURPOSE

To compare the safety and the visual outcomes of two experienced cataract surgeons who converted from extracapsular cataract extraction (ECCE) to manual small incision cataract surgery (MSICS) during a campaign for the prevention of blindness.

METHODS

Two surgeons used the ECCE technique (ECCE group) during a campaign in Burkina Faso on 93 consecutive cataract patients with a corrected distance visual acuity (CDVA) <20/80 in the best eye. Both surgeons used MSICS for the first time on 98 consecutive cases in another campaign in Kenya after theoretical instructional courses.

RESULTS

There were no significant differences in CDVA at 3 months postoperatively. There were 69% of eyes with uncorrected distance visual acuity ≥20/60 in the MSICS group and 49% eyes in the ECCE group. Spherical equivalents ranged between -1D and +1D in 55% of the MSICS group versus 43% in the ECCE group. There were significant differences in the changes in the vertical component of astigmatism (J45) but not the horizontal (J0) component. There were no significant differences in the intraoperative complications. The most common postoperative complication was corneal edema on the first day in 40.86% and 19.38% of the ECCE and MSICS groups, respectively.

CONCLUSION

Transitioning from ECCE to MSICS for experienced cataract surgeons in surgical campaigns is safe. The rate of complications is similar for both techniques. Slightly better visual and refractive outcomes can be achieved due to the decreased induction of corneal astigmatism.