Judith Perrigin

Houston Myopia Control Study: a randomized clinical trial. Part II. Final report by the patient care team.

ABSTRACT In a randomized clinical trial designed to test the efficacy of bifocal lenses for the control of juvenile myopia, each of 207 children between the ages of 6 and 15 years wore single vision lenses, +1.00 D add bifocals, or +2.00 D add bifocals for a period of 3 years. For the 124 subjects who completed the study, the mean changes in refraction were found to be ‐0.34 D per year for subjects wearing single vision lenses, ‐0.36 D per year for those wearing +1.00 D add bifocals, and ‐0.34 D per year for those wearing +2.00 D add bifocals. These differences were not statistically significant. When subjects in all three treatment groups were combined, it was found that the rate of progression tended to be the most rapid for subjects who entered the study at an early age with a large amount of myopia, and tended to be the least rapid for subjects who entered the study at a later age with a small amount of myopia. It was also found that subjects having with‐the‐rule astigmatism progressed more slowly than those having no astigmatism or against‐the‐rule astigmatism.

Silicone-acrylate contact lenses for myopia control : 3-year results

One hundred myopic children between the ages of 8 and 13 years were fitted with Paraperm O2plus silicone-acrylate contact lenses. After 3 years of lens wear, the mean increase in myopia for the 56 subjects remaining in the study was 0.48 D (±0.70) D as compared with 1.53 (±0.81) D for a group of spectacle-wearing myopes matched for initial age and initial refractive error. The mean change in corneal refracting power for the contact lens wearers was a decrease (corneal flattening) of 0.37 (±0.32) D. Assuming that little or no corneal change would have occurred in the absence of the contact lenses, we may conclude that corneal flattening (as measured by the keratometer) accounts for less than half of the effect of contact lenses in controlling myopia progression. A possible explanation for this disparity is that although the keratometer provides a valid measurement of corneal refracting power for a “normal” cornea, it fails to provide a valid measurement for a cornea that has been flattened by wearing a contact lens.

Use of silicone-acrylate contact lenses for the control of myopia: results after two years of lens wear

Although a number of reports have been published concerning the use of polymethyl methacrylate (PMMA) contact lenses for the control of myopia, there have been no reports of the use of gas permeable contact lenses for this purpose. In the study reported here, 100 myopic children between the ages of 8 and 13 years were fitted with Paraperm O2plus silicone-acrylate contact lenses to be worn for a period of 3 years. Lenses were fitted by the alignment method, most lenses having diameters from 8.5 to 9.0 mm. At the end of 2 years 60 subjects remained in the study, 53 of whom were wearing their lenses on a regular basis and the other 7 were irregular wearers. Mean increases in myopia during the 2-year period were found to be 0.28 D for the subjects who wore their lenses regularly and 0.93 D for the irregular wearers, compared to 0.80 D for a group of 31 age-matched single vision spectacle lens wearers. Mean corneal refracting power was found to decrease (the cornea flattened) 0.33 D for the regular wearers as compared to an increase of 0.14 D for the irregular wearers and a decrease of 0.13 D for the spectacle wearers. Mean changes in axial length were an increase of 0.1 mm for the regular wearers, an increase of 0.4 mm for the irregular wearers, and an increase of 0.6 mm for the spectacle wearers. These results show that approximately one-half of the effect of the contact lenses in controlling myopia can be attributed to corneal flattening and support Stones suggestion that contact lenses worn by young myopes may have an effect in controlling the axial length of the eye.

Rigid gas-permeable contact lenses for myopia control: effects of discontinuation of lens wear.

Conventionally fitted Paraperm O2plus contact lenses were worn for 44 months by 23 myopic children, who discontinued lens wear for 2.5 months and then resumed lens wear with Fluoroperm 30 lenses for a period of 8 months. Mean changes in myopia were: (1) an increase of 0.76 D during the initial 44 months of lens wear, (2) a further increase of 0.27 D during the 2.5 months when lenses were not worn, and (3) a decrease of 0.02 D during the 8-month period of Fluoroperm 30 lens wear. These results show that the effect of rigid gas-permeable lenses on myopia progression is diminished if lens wear is discontinued; however, the mean increase in myopia for these children was significantly less than would have been expected if glasses had been worn for the entire 54.5-month period. The results after discontinuation and then resumption of lens wear show that the effect of contact lenses in controlling the progression of myopia could not be accounted for entirely on the basis of corneal flattening as measured by the keratometer, therefore reinforcing the conclusion that corneal flattening due to rigid lens wear takes place primarily at the corneal apex, rather than in the zone of the cornea measured by the keratometer.

Houston Myopia Control Study: a randomized clinical trial. Part I. Background and design of the study.

ABSTRACT The Houston Myopia Control Study is a 3‐year randomized clinical trial in which each of 213 myopic children was placed in either a single vision (standard treatment) group, a +1.00 D add treatment group, or a +2.00 D add treatment group, on the basis of a randomized procedure. Subjects for the three treatment groups were matched on the basis of sex, age, and the initial amount of myopia. The study involves two groups of investigators: an evaluation team, whose task has been to evaluate candidates before entering the study and to reevaluate each subject on a yearly basis for the 3‐year period, and a patient care team, whose task has been to prescribe glasses for each subject as well as to counsel subjects and their parents in the correct use of the glasses and to provide a follow‐up examination every six months for the duration of the study. Once the glasses had been prescribed, members of the evaluation team were not permitted to know which subjects wore single vision lenses and which wore bifocals. In the interest of good patient care, members of the patient care team knew which subjects wore single vision lenses and which wore +1.00 D add or +2.00 D add bifocals. In this report, the authors discuss theories concerning the etiology of myopia, methods that have been used in an attempt to control the progression of myopia, and the design of the current study. Further reports will present the results of the study on the basis of the data collected by each of the two study teams.

A case of fungal keratitis: A clinical and in vivo confocal microscopy assessment

A presumed case of fungal keratitis is presented. Confocal images highlight the advantage of using such technology to follow therapeutic progress, particularly when standard laboratory testing is inconclusive. This case also demonstrates the importance of continued patient education regarding overall compliance and lens care.

Three-way comparison of Retinoscopy, subjective, and dioptron nova refractive findings

On the basis of routine clinical findings taken on a group of 100 patients serving as subjects in the Houston Myopia Control study, a three-way comparison was made between retinoscopy, subjective, and Dioptron Nova refractive findings. Retinoscopy and subjective findings compared very favorably, mean differences being -0.01 D for spherical equivalent power and -0.05 D for cylinder power. Dioptron and retinoscopy findings differed by -0.30 D for spherical equivalent power and -0.13 D for cylinder power, whereas Dioptron and subjective findings differed by -0.33 D for spherical equivalent power and -0.18 D for cylinder power.

Comparison of Dioptron Nova refractive data with conventional refractive data.

Refractive data obtained by means of the Dioptron Nova Diagnostic Eye Computer were compared to data obtained by conventional clinical refraction on a group of 236 clinic patients. Spherical equivalent power data were found to average -0.32 D more for Dioptron Nova data than for clinical data, whereas spherical power data averaged -0.25 D more for Dioptron Nova data than for clinical data, and cylinder power averaged -0.12 D more for Dioptron Nova data. Dioptron and clinical data were found to be within +/- 0.50 D of each other for 74% of eyes for spherical equivalent power, for 83% of eyes for spherical power, and for 91% of eyes for cylinder power. Cylinder axis data were found to be within +/- 10 degrees for the two methods for 78% of eyes.

Comparison of American optical SR-IV refractive data with clinical refractive data on a group of myopic children.

Previous studies involving the American Optical SR-III Subjective Refraction System have indicated that refractive data for adults and for populations of mixed age groups compare favorably with conventional refractive data. However, no data concerning children, as a group, have been available. As a part of a 3-year Myopia Control Study being conducted at the University of Houston, 131 myopes between the ages of 6 and 15 years have been refracted by means of both the redesigned SR-IV Programmed Subjective Refractor and conventional clinical procedures. The results indicated that for the majority of subjects, the refractive data obtained by means of the SR-IV differed by no more than 0.25 D from data obtained by conventional procedures. SR-IV and clinical refractive data were also compared for a group of 30 second year optometry students, and agreement for the two methods was found to compare favorably with agreement of clinical refractive data obtained by two or more examiners.

Opaque contact lens color choices among women of different ethnic groups

Purpose. The opaque contact lens (OCL) market is profitable and expanding. This pilot study sought to identify OCL color preferences among women of three ethnic groups, African American (A), white (W), and Hispanic Americans (H). Methods. Sixty-three brown-eyed female subjects (19 A; 22 W; 22 H), 18 to 35 years of age, with uncorrected near visual accuity of at least 20/50 were recruited. Each subject was presented with OCLs of three different color pattern designs in each of four colors (blue, green, gray, and hazel). The subjects viewed their appearance in a mirror while wearing each lens. Once all lenses had been observed, the subjects chose their lens color preference. Results. Using the nonparametric Kruskal-Wallis test, an ethnic preference was shown for all but the gray contact lenses. In group A 47.4% rated the hazel lens as their first choice whereas 0% chose the blue lens. In contrast, 45.5% of group C chose the blue lens over the other colors but did not favor the hazel lens, which was their first choice only 4.5% of the time. Group H demonstrated the most diversity in color preference, however, 36.4% chose green as their overall lenscolor preference. Conclusions Distinct differences exist in OCL color preferences among the three ethnic groups studied. Improved understanding of this ethnic difference could increase the efficiency of the trial lens process while possibly decreasing inventory costs when one ethnic group dominates a practice patient base.