Effects of Ocular Parameters on Diameter of Well-fitted Rigid Gas Permeable Lens in Koreans

PURPOSE: To compare the differences of parameters of 9.3 mm and 8.8 mm rigid gas permeable lenses (RGP lenses) that were prescribed by trial lens fitting. METHODS: Ninety-three eyes of 49 patients were prescribed RGP contact lenses (YK spherical lens, Lucid Korea, Bonghwa, Korea) by a single ophthalmologist at the same hospital. We analyzed the differences of parameters of 9.3 mm and 8.8 mm rigid gas permeable lenses (RGP lenses) that were prescribed by trial lens fitting. Steep keratometric value (Ks), flat keratometric value (Kf), and corneal astigmatism (Kast) were measured by keratometer. Simulated steep keratometric value (Sim Ks), simulated flat keratometric value (Sim Kf), simulated corneal astigmatism (Sim Kast), white to white corneal diameter (WTW), and eccentricity were measured by corneal topography. We also analyzed the differences of back optic zone radius (BOZR) and lens power between the two groups. RESULTS: In this study, 40 eyes wearing 8.8 mm lenses and 53 eyes wearing 9.3 mm lenses were included. Keratometric value and eccentricity were significantly higher in the 8.8 mm lens group, while WTW and BOZR were significantly lower. Corneal astigmatism (Kast, Sim Kast) and lens power were not significantly different between the groups. CONCLUSIONS: RGP lenses with a smaller diameter were likely to be prescribed to patients with higher keratometric value, higher eccentricity, and shorter WTW, and the average BOZR of the prescribed RGP lenses with a smaller diameter was likely to be steeper.

Comparison of Objective and Subjective Changes Induced by Multiple-Pinhole Glasses and Single-Pinhole Glasses

Multiple-pinhole (MPH) glasses are currently sold in many countries with unproven advertisements; however, their objective and subjective effects have not been investigated. Therefore, to investigate the effects of MPH glasses excluding the single-pinhole (SPH) effect, we compared the visual functional changes, reading speed, and ocular discomfort after reading caused by MPH and SPH glasses. Healthy 36 participants with a mean age of 33.1 years underwent examinations of pupil size, visual acuity (VA), depth of focus (DOF), and near point accommodation (NPA); tests for visual field (VF), contrast sensitivity (CS), stereopsis, and reading speed; and a survey of ocular discomfort after reading. Both types of pinhole glasses enlarged pupil diameter and improved VA, DOF, and NPA. However, CS, stereopsis, and VF parameters deteriorated. In comparison with SPH glasses, MPH glasses induced smaller pupil dilation (5.3 and 5.9 mm, P < 0.001) and showed better VF parameters with preserved peripheral VF. However, no significant difference was observed for VA, DOF, NPA, stereopsis, and CS. Reading speed using pinhole glasses was significantly slower than baseline; SPH glasses showed the slowest reading speed. Both types of glasses caused significant ocular discomfort after reading compared with baseline, and symptoms were worst with MPH glasses. In conclusion, both types of pinhole glasses had positive effects due to the pinhole effect; however, they had negative effects on VF, CS, stereopsis, reading speed, and ocular discomfort. In spite of the increased luminance and preserved peripheral VF with MPHs, these glasses caused more severe ocular discomfort than SPH glasses. This clinical trial was registered at www.ClinicalTrials.gov (Identifier: NCT02572544).

Fitting the Miniscleral Contact Lens in Patients with Corneal Abnormalities

PURPOSE: To evaluate the clinical results of fitting the miniscleral contact lens (MSD; Happy Vision Corp., Anyang, Korea) in patients with corneal abnormalities. METHODS: Thirty-eight patients (56 eyes) fitted with MSD lenses were recruited for this study. Clinical indication, visual acuity, degree of comfort, mean wearing time, parameters of the finally prescribed lenses, number of fittings with trial lenses, success rate with the first prescribed lens, and adverse events were evaluated. RESULTS: Forty-two (75%) of 56 eyes were enrolled in this study due to keratoconus. Other conditions included Stevens-Johnson syndrome (6 eyes, 11%), high postkeratoplasty astigmatism (3 eyes, 5%), corneal scarring (3 eyes, 5%), and ectasia after laser in situ keratomileusis (LASIK; 2 eyes, 4%). The mean log MAR visual acuity improved from 1.01 ± 0.64 to 0.13 ± 0.19 after wearing lenses (p= 0.0001). In 53 eyes (94.6%), patients reported the miniscleral contact lenses to be comfortable, and the mean daily wear time was 12.9 ± 2.5 hours. The mean sagittal depth of finally prescribed lenses was 4.67 ± 0.37 mm (3.7-5.4). An average of 3.3 ± 1.5 (1-7) trials were needed for the trial fitting, and the average number of re-prescriptions to achieve the optimal fitting was 1.5 ± 0.48 (1-3). One patient discontinued the lenses after 3 months due to discomfort. CONCLUSIONS: Miniscleral contact lenses are a good alternative for patients with corneal abnormalities and result in both successful visual outcome and comfort.

Effect of Toric Orthokeratology Lenses in Patients with Limbus to Limbus Corneal Astigmatism

PURPOSE: To report the efficacy of toric orthokeratology lenses in patients with astigmatism within 1.5 D having difficulty in wearing spherical orthokeratology lenses due to the limbus-to-limbus corneal astigmatism. METHODS: Twenty-three eyes of 16 patients with limbus-to-limbus corneal astigmatism who had been wearing toric orthokeratology lenses for more than 6 months were recruited. The uncorrected visual acuity (UCVA), refractive error, and keratometric changes including eccentricity before and after wearing lenses were compared, and the correlations between corneal astigmatism as well as refractive astigmatism and lens toricity were assessed. RESULTS: After wearing the lens, UCVA (log MAR) significantly improved from 0.61 +/- 0.22 to 0.05 +/- 0.08 (p < 0.001). Myopia and spherical equivalent were also reduced significantly (p < 0.001 and p < 0.001, respectively). While Simulated K (Sim K) tended to be more flattened (p < 0.001) and the eccentricity showed significant decrease (p < 0.001), corneal and refractive astigmatism were not changed significantly (p = 0.330 and p = 0.124, respectively). Correlations between corneal and refractive astigmatism and lens toricity were not statistically significant (r = 0.244, p = 0.300; r = -0.051, p = 0.832). No patients showed lens decentration or visual discomfort. CONCLUSIONS: Corneal topography was essential in patients who had difficulty in wearing spherical orthokeratology lenses due to the limbus-to-limbus corneal astigmatism. Toric orthokeratology lenses may be an effective treatment option in patients with limbus-to-limbus corneal astigmatism.

Effect of Toric Orthokeratology Lenses in Patients with Limbus to Limbus Corneal Astigmatism

PURPOSE: To report the efficacy of toric orthokeratology lenses in patients with astigmatism within 1.5 D having difficulty in wearing spherical orthokeratology lenses due to the limbus-to-limbus corneal astigmatism. METHODS: Twenty-three eyes of 16 patients with limbus-to-limbus corneal astigmatism who had been wearing toric orthokeratology lenses for more than 6 months were recruited. The uncorrected visual acuity (UCVA), refractive error, and keratometric changes including eccentricity before and after wearing lenses were compared, and the correlations between corneal astigmatism as well as refractive astigmatism and lens toricity were assessed. RESULTS: After wearing the lens, UCVA (log MAR) significantly improved from 0.61 +/- 0.22 to 0.05 +/- 0.08 (p < 0.001). Myopia and spherical equivalent were also reduced significantly (p < 0.001 and p < 0.001, respectively). While Simulated K (Sim K) tended to be more flattened (p < 0.001) and the eccentricity showed significant decrease (p < 0.001), corneal and refractive astigmatism were not changed significantly (p = 0.330 and p = 0.124, respectively). Correlations between corneal and refractive astigmatism and lens toricity were not statistically significant (r = 0.244, p = 0.300; r = -0.051, p = 0.832). No patients showed lens decentration or visual discomfort. CONCLUSIONS: Corneal topography was essential in patients who had difficulty in wearing spherical orthokeratology lenses due to the limbus-to-limbus corneal astigmatism. Toric orthokeratology lenses may be an effective treatment option in patients with limbus-to-limbus corneal astigmatism.

Long-Term Effect and Safety of Contact Lenses for Keratoconus

PURPOSE: To evaluate the long-term clinical effect and safety of YK-KC lens(R) (LucidKorea Ltd., Seoul, Korea) for keratoconus. METHODS: In this study we investigated 152 keratoconic eyes fitted with YK-KC lens(R) and followed up for at least 5 years. We assessed retrospectively self-reported patient comfort, best corrected visual acuity, corneal topographic indices before and after contact lens fitting and complications during contact lens wearing. RESULTS: The study included 57 male and 40 female patients with a mean age of 28.6 +/- 8.5 years. The mean follow-up was 8.0 +/- 2.9 years. Regarding lens comfort, 126 eyes (82.9%) showed self-reported comfort for YK-KC lenses(R). The mean best corrected visual acuity (log MAR) improved from 0.49 +/- 0.42 before lens fitting to 0.19 +/- 0.27 after lens wearing, which was statistically significant (p < 0.001). Based on the keratometric values, after contact lens fitting both Simulated keratometry (Sim K) max and Sim K min tended to be steeper, but these differences were not statistically significant (p = 0.66 and 0.11, respectively). There were no statistically significant differences between the values before and after fitting with respect to the astigmatic powers (p = 0.22). Complications observed included punctate or coalesced epithelial corneal staining in 24 eyes (16%), however, persistent full-thickness epithelial defect was not observed. CONCLUSIONS: The YK-KC lens(R) in patients with keratoconus can provide excellent visual improvement and comfort without any significant influence on the progression of keratoconus or corneal complications during a long-term follow-up period.

Long-Term Effect and Safety of Contact Lenses for Keratoconus

PURPOSE: To evaluate the long-term clinical effect and safety of YK-KC lens(R) (LucidKorea Ltd., Seoul, Korea) for keratoconus. METHODS: In this study we investigated 152 keratoconic eyes fitted with YK-KC lens(R) and followed up for at least 5 years. We assessed retrospectively self-reported patient comfort, best corrected visual acuity, corneal topographic indices before and after contact lens fitting and complications during contact lens wearing. RESULTS: The study included 57 male and 40 female patients with a mean age of 28.6 +/- 8.5 years. The mean follow-up was 8.0 +/- 2.9 years. Regarding lens comfort, 126 eyes (82.9%) showed self-reported comfort for YK-KC lenses(R). The mean best corrected visual acuity (log MAR) improved from 0.49 +/- 0.42 before lens fitting to 0.19 +/- 0.27 after lens wearing, which was statistically significant (p < 0.001). Based on the keratometric values, after contact lens fitting both Simulated keratometry (Sim K) max and Sim K min tended to be steeper, but these differences were not statistically significant (p = 0.66 and 0.11, respectively). There were no statistically significant differences between the values before and after fitting with respect to the astigmatic powers (p = 0.22). Complications observed included punctate or coalesced epithelial corneal staining in 24 eyes (16%), however, persistent full-thickness epithelial defect was not observed. CONCLUSIONS: The YK-KC lens(R) in patients with keratoconus can provide excellent visual improvement and comfort without any significant influence on the progression of keratoconus or corneal complications during a long-term follow-up period.

Effect of Toric Orthokeratology Lenses on Patients with More Than 1.5 Diopter of Corneal Astigmatism

PURPOSE: To report the effect of toric orthokeratology lenses on myopic patients who have more than 1.5 diopter (D) of corneal astigmatism. METHODS: Seventeen patients (24 eyes) who wore toric orthokeratology lenses for more than 6 months were recruited for this study. The uncorrected visual acuity (UCVA), refractive error and keratometric changes including eccentricity before and after wearing lenses were compared. The correlations between corneal astigmatism as well as refractive astigmatism and lens toricity and between corneal astigmatism and improvement of UCVA after lens fitting were assessed. RESULTS: After wearing lenses, UCVA (log MAR) was significantly improved from 0.93 +/- 0.13 to 0.09 +/- 0.07 (p < 0.001). Myopia changed from -4.53 +/- 1.55 D to -0.67 +/- 0.80 D (p < 0.001), refractive astigmatism from -1.48 +/- 0.71 D to -0.99 +/- 0.72 (p = 0.008) and spherical equivalent from -5.27 +/- 1.56 D to -1.12 +/- 0.92 D (p < 0.001). Simulated K (Sim K) tended to be more flat (p < 0.001) and the eccentricity was significantly decreased from 0.45 +/- 0.08 to -0.69 +/- 0.45 (p < 0.001), but corneal astigmatism was not significantly changed from 2.05 +/- 0.41 D to 2.01 +/- 0.98 D (p = 0.803). Correlation between corneal astigmatism and lens toricity was statistically significant (r = 0.526, p = 0.012) but not between refractive astigmatism and lens toricity (r = 0.218, p = 0.329). The amount of corneal astigmatism was not correlated with the improvement of uncorrected visual acuity after lens fitting (r = 0.1804, p = 0.399). CONCLUSIONS: Toric orthokeratology lenses might be an effective treatment in patients with corneal astigmatism who cannot be fitted with spherical orthokeratology lenses. Lens toricity was correlated with corneal astigmatism and the amount of corneal astigmatism did not affect the improvement of uncorrected visual acuity after lens fitting.

Correction of Limbus-to-Limbus Corneal Astigmatism with Toric Orthokeratology Lenses

PURPOSE: To report the efficacy of toric orthokeratology lenses in a patient with corneal astigmatism within 1.5 D having difficulty wearing spherical orthokeratology lenses because of limbus-to-limbus corneal astigmatism. CASE SUMMARY: An 11-year-old boy who wanted to wear orthokeratology lenses had a refractive error of -4.75 D sph = -1.00 D cyl 180 in the right eye and -4.50 D sph = -1.25 D cyl 180 in the left eye. The corneal astigmatism was 1.19 D and 1.19 D, respectively, and limbus-to-limbus corneal astigmatism was observed in topography. After wearing spherical orthokeratology lenses, the patient complained of monocular diplopia and both lenses were found to be displaced nasally. Toric orthokeratology lenses were prescribed for centration of lenses and resulted in significant improvement of uncorrected visual acuity of 20/20, refractive error of +0.75 D sph = -0.50 D cyl 170 in the right eye and +0.50 D sph = -0.50 D cyl 160 in the left eye, and centration of lenses for the 12-month follow-up period. CONCLUSIONS: Toric orthokeratology lenses should be considered if spherical orthokeratology lenses are not effective even in patients having less than 1.5 D of corneal astigmatism because of limbus-to-limbus corneal astigmatism.

The Inhibitory Effect of Myopic and Astigmatic Progression by Orthokeratology Lens

PURPOSE: To investigate the clinical effects of orthokeratology lens wear on inhibition of the progression of Korean myopia and astigmatism. METHODS: The authors reviewed out-patient records of 144 eyes of 74 patients wearing orthokeratology lenses. The cycloplegic refraction and keratometry before and after wearing the lens were compared. The 190 eyes wearing spectacles were included into the control group. We evaluated the relationship between orthokeratology lens wear and control group according to age, initial myopia, initial astigmatism, myopic progression, astigmatic progression and duration of orthokeratology lens wearing. RESULTS: The mean cycloplegic refractive error of spherical equivalent was -3.36 +/- 1.96 diopters (D) in the patients wearing orthokeratology lenses, the mean astigmatism was -0.86 +/- 0.72 D, and the mean wearing period was 3.41 +/- 1.5 years. The mean myopic progression was 0.25 +/- 0.31 D in lens wearing, and 0.62 +/- 0.39 D in glasses wearing, respectively. There were statistically significant differences between lens and glasses wearing group (t-test, p 0.01). CONCLUSIONS: The orthokeratology lens was found to be effective in suppression of the progression of Korean myopia and astigmatism, compared with the glasses.