The Correlations between Horizontal and Vertical Peripheral Refractions and Human Eye Shape Using Magnetic Resonance Imaging in Highly Myopic Eyes.

The aim of this study was to determine the relationship between relative peripheral refraction and retinal shape by 2-D magnetic resonance imaging in high myopes. Thirty-five young adults aged 20 to 30 years participated in this study with 16 high myopes (spherical equivalent < -6.00 D) and 19 emmetropes (+0.50 to -0.50 D). An open field autorefractor was used to measure refractions from the center out to 60° in the horizontal meridian and out to around 20° in the vertical meridian, with a step of 3 degrees. Axial length was measured by using A-scan ultrasonography. In addition, images of axial, sagittal, and tangential sections were obtained using 2-D magnetic resonance imaging. The highly myopic group had a significantly relative peripheral hyperopic refraction and showed a prolate ocular shape compared to the emmetropic group. The highly myopic group had relative peripheral hyperopic refraction and showed a prolate ocular form. Significant differences in the ratios of height/axial (1.01 ± 0.02 vs. 0.94 ± 0.03) and width/axial (0.99 ± 0.17 vs. 0.93 ± 0.04) were found from the MRI images between the emmetropic and the highly myopic eyes (p < 0.001). There was a negative correlation between the retina's curvature and relative peripheral refraction for both temporal (Pearson r = -0.459; p < 0.01) and nasal (Pearson r = -0.277; p = 0.011) retina. For the highly myopic eyes, the amount of peripheral hyperopic defocus is correlated to its ocular shape deformation. This could be the first study investigating the relationship between peripheral refraction and ocular dimension in high myopes, and it is hoped to provide useful knowledge of how the development of myopia changes human eye shape.

Bilateral corneal erosion due to retail purchase of unfitted prescription contact lenses: a case report.

PURPOSE: We report a case demonstrating the importance of trial fitting before the dispensing of prescription contact lenses. METHODS: The patient was an 18-year-old computer-using experienced hydrogel lens wearer who ran out of contact lens supply. The patient purchased a brand new box of daily disposable lenses from a retail store having known his back vertex power. No trial fitting of the lenses was performed at the point of sale. RESULTS: After a day of wear of the lenses with significant computer use, the patient removed them and went to bed, but the next morning, presented on an emergency basis with severe pain and blurry vision in both eyes. Slit lamp examination showed significant bilateral corneal erosions that were treated with prophylactic antibiotics, steroids, and lubricants. A bandage contact lens was further given to his right eye. The characteristics of the daily disposable lenses and his computer overuse were viewed as contributing factors to the complication. CONCLUSIONS: The dispensing and wear of prescription contact lenses without a proper selection and fit led to bilateral corneal erosions in this patient. Though our case occurred in Taiwan, a jurisdiction where prescription contact lens sale is not regulated, the authors note that such a scenario could occur in jurisdictions where contact lens sale is regulated if, after confirmation of back vertex power, no effort is made to ensure that a purchased lens is safe or appropriate for a patient, such as when lenses are purchased through internet suppliers or in certain commercial retail settings.

Mistaken diagnosis of keratoconus because of corneal warpage induced by hydrogel lens wear.

PURPOSE: We report a case of corneal warpage secondary to hydrogel lens wear that was initially mistaken as a case of keratoconus. METHODS: A 26-year-old Chinese female hydrogel lens wearer presented with an interest in refractive surgery. After topographies and pachymetries were performed, keratoconus was initially diagnosed for her right eye and suspect keratoconus diagnosed for her left eye. This conclusion was felt to be confirmed at a follow-up visit 1 week later, but keratoconus contact lens treatment was delayed because of the presence of superficial punctate keratitis. RESULTS: After 8 weeks without lens wear, corneal maps were performed again. The maps now showed regular with-the-rule astigmatism, and none of the previous evidence of keratoconus. Central pachymetries were also normal. CONCLUSIONS: Soft contact lens wear can induce corneal warpage mimicking keratoconus. Had the standard treatment for keratoconus been implemented before resolution of the warpage, it could have proven injurious to the patient, because the treatment itself could have provided an impetus for the protrusion to remain or perhaps even progress. Our case gives clinicians reason to pause when dealing with contact lens wearers presenting with corneal curvature irregularities such as keratoconus or ectasia, because of the possibility of lens-induced warpage.