Correlation Between Anterior Corneal Elevation Differences in Main Meridians and Corneal Astigmatism.

PURPOSE: To assess the correlation between anterior corneal elevation (ACE) and anterior corneal astigmatism (ACA) obtained with two different topographers in healthy subjects at different corneal diameters. METHODS: A retrospective, comparative, and observational study was conducted. Topography data from 305 patients obtained with the Oculus Pentacam (Oculus, Wetzlar, Germany) and Sirius (CSO, Florence, Italy) systems were collected. Subjects were divided into four groups depending on the magnitude of ACA. The ACE was evaluated in the principal meridians at 2, 3, and 4 mm from the corneal apex. The difference in ACE between meridians (ACE-M) and in superior-inferior and nasal-temporal semimeridians (ACE-SM) was calculated. RESULTS: A strong positive correlation between ACE-M and ACA with both topographers was found for all corneal diameters (P<0.001). A linear equation to calculate the ACE-M differences as a function of the astigmatism at 8 mm of diameter was obtained: y=23.417x+1.40, where y is ACE-M in microns and x is ACA in diopters. Significant differences in ACE along SM were found for all groups studied according to the magnitude of ACA for the horizontal SM (P>0.001). The temporal meridian was more elevated at 4- and 6-mm diameters, and the nasal semimeridian was the most elevated for 8 mm. CONCLUSION: Anterior corneal astigmatism and elevation differences are strongly correlated, providing more corneal topography knowledge that could be applied in the contact lens fitting. A toric orthokeratology lens may be indicated in ACA greater than 0.75 D.

Clinical performance of a new hybrid contact lens for keratoconus.

OBJECTIVES: To compare the clinical performance of the Clearkone hybrid contact lens for the treatment of keratoconus against the habitual contact lens of the patients. METHODS: A total of 33 eyes from 18 patients were fitted with the Clearkone. High- and low-contrast visual acuity (HCVA and LCVA), central corneal thickness (CCT), and contrast sensitivity acuity (CSF) were recorded with habitual lenses (prestudy visit) and after 1 week, 15 days, and 1 month of wear of prescribed Clearkone. Subjective vision and comfort were rated using visual analogue scales (VAS). RESULTS: Three patients discontinued the study, one because of diffuse corneal staining after 1 day of use and the other two because of extreme discomfort. The rest of the patients completed the 1-month study. High contrast visual acuity and LCVA (logMAR) improved significantly from 0.16 ± 0.12 and 0.44 ± 0.22, respectively, with the patient's habitual contact lenses to -0.006 ± 0.058 and 0.23 ± 0.13 after 1 day wearing Clearkone, remaining significant during all follow-up visits (P<0.001; repeated measures analysis of variance [RM-ANOVA]). There were no statistically significant differences in the mean CCT. The improvement of CSF was statistically significant with hybrid contact lenses prescribed compared with the patient's habitual contact lenses (P<0.001; RM-ANOVA test). Improvement in VAS score, with prescribed Clearkone, was statistically significant for comfort (P=0.043; RM-ANOVA test), but not for the subjective vision (P=0.759; RM-ANOVA test). CONCLUSIONS: Clearkone provides an improvement in visual acuity, contrast sensitivity, and subjective comfort in patients with keratoconus when compared with other contact lens options. However, clinicians must get specific training to fit the lens and be aware of potential adverse events.

Accommodation response and spherical aberration during 1-Year of orthokeratology lens wear and after discontinuation.

BACKGROUND: To assess accommodation and spherical aberration changes during one year of orthokeratology lens wear and one month after lens cessation. METHODS: A prospective, randomized, longitudinal study was conducted on forty-seven young healthy subjects at the Optometry Clinic of the Complutense University of Madrid (Spain). Non-cycloplegic refraction, high and low uncorrected visual acuity, high and low best corrected visual acuity, accommodative lag, horizontal near phoria, corneal topography, and high-order aberrations were performed at baseline, 1-day, 1-week, 1-, 6- and 12-months of lens wear and after one month of wash out period. p < 0.05 was considered as statistically significant. RESULTS: Spherical equivalent refraction (SE) was -3.23 ± 1.57D at baseline and -0.36 ± 0.64D after 12-months of lens wear, while accommodative lag changed from 0.53 ± 0.39D to 0.15 ± 0.29D after one year of lens wear. No significant differences were found when comparing SE at baseline and after one month of lens cessation (p > 0.05). A high correlation was found between the accommodative lag at baseline and after 12 M of lens wear. 22 out of 25 subjects with exophoria at baseline showed a significant reduction in the deviation at 12-months (p < 0.05). Total spherical aberration increased during all visits due to the lens wear (p < 0.05) although internal spherical aberration showed a significant decrease for 1-week, 1-month and 12-month visits (p < 0,05). CONCLUSION: Orthokeratology lenses may change the accommodative response of the patient as a reduction on accommodative lag on exophoric patients and an overall increase on the internal spherical aberrations was found during treatment but return to nearly baseline values when cessation.

Is soft toric contact lenses fitting a feasible option to improve optical quality and visual performance in corneal ectasia?

OBJECTIVES: To assess the feasibility of fitting soft toric contact lenses (STCL) in corneal ectasias and their impact on optical quality and visual performance. METHODS: A total of 22 eyes were fitted with a molded STCL: 11 eyes/9 subjects with corneal ectasia and 11 healthy eyes/11 subjects. Wavefront aberrations were analyzed using a Hartmann-Shack aberrometer. Visual performance was measured under photopic (85 cd/m 2) and mesopic (≤3 cd/m 2) conditions. High-(96 %) and low- (10 %) contrast VA (HCVA and LCVA respectively) were assessed using the ETDRS charts and contrast sensitivity (CS) using the Pelli-Robson chart. RESULTS: After STCL fitting in the ectatic corneas, oblique astigmatism increased 0.15±0.17 µm and 0.34 ± 0.36 µm for 3 mm- and mesopic pupil diameters, respectively. Mean defocus decreased 1.41 ± 0.36 µm and 2.17 ± 0.85 µm for the same pupil diameters. More positive values of vertical coma were found with a change of 0.05 ± 0.06 µm and 0.12 ± 0.10 µm for 3 mm and mesopic pupil diameters, respectively. Comparing changes between both groups, with a 3 mm pupil aperture, statistically significant differences (p < 0.05) were detected in oblique astigmatism, defocus, vertical secondary trefoil and horizontal secondary coma. In the group with corneal ectasia, photopic HCVA and LCVA improved 0.09 ± 0.11 logMAR and 0.12 ± 0.15 logMAR respectively. In mesopic conditions, HCVA, LCVA and CS improved 0.11 ± 0.12 logMAR, 0.18 ± 0.15 logMAR and 0.11 ± 0.07 log. units, respectively. CONCLUSIONS: The analyzed molded soft toric contact lens is a feasible option for good vision in corneal ectasia with moderate irregularity and negative vertical coma.

Changes in visual quality with soft contact lenses after the instillation of hyaluronic acid eye drops.

PURPOSE: To evaluate the changes in visual function and anterior surface aberrations during soft contact lens (SCL) wear after the instillation of hyaluronic acid (HA) eye drops with different viscosity. METHODS: A prospective, randomized, and participant-masked study was performed. Twenty healthy participants (25.4 ± 2.6 years) were evaluated. Hydrogel (Ocufilcon D) and silicone-hydrogel (Somofilcon A) SCL were randomly assigned to both eyes of the same participant. Visual function in terms of high- and low-contrast corrected distance visual acuity (CDVA) and anterior contact lens surface aberrations (RMS HOA) were measured before and after the instillation, at different times, of different eye drops: saline (control) and 0.1%, 0.2%, and 0.3% HA. RESULTS: Compared with the saline solution, during hydrogel SCL wear, there was an improvement (P < 0.05) in high-contrast CDVA after 3 and 10 min with 0.1% HA, and after 5 and 20 min with 0.2% HA. During silicone-hydrogel SCL wear, there was a deterioration (P < 0.05) in high-contrast CDVA after 1 and 30 min with 0.3% HA. Additionally, during silicone-hydrogel SCL wear, there was also a deterioration (P < 0.05) in low-contrast CDVA after 5 and 20 min with 0.3% HA. In terms of RMS HOA, there were no clinically relevant changes with both SCL. CONCLUSIONS: The instillation of HA eye drops could have a different effect on visual quality depending on their concentration of HA, the contact lens material, its surface ionicity, or other physicochemical properties that should be studied in future studies.

Repeatability of Aberrometry-Based Automated Subjective Refraction in Healthy and Keratoconus Subjects.

PURPOSE: To compare the intersession repeatability of the Eye Refract, a new instrument to perform aberrometry-based automated subjective refraction, on healthy and keratoconus subjects. MATERIALS AND METHODS: A cross-sectional and randomized study was performed. A total of 64 participants were evaluated in the study, selecting one eye per participant randomly. The sample was divided into two different groups: 33 healthy subjects (38.85 ± 13.21 years) and 31 with keratoconus (37.29 ± 11.37 years). Three refractions per participant with the Eye Refract were performed on three different days, without cycloplegia. The repeatability analysis of refractive variables (M, J0, and J45), binocular corrected distance visual acuity (BCDVA), and spent time in refraction was performed in terms of repeatability (S r), its 95% confidence interval (r), and intraclass correlation coefficient (ICC). RESULTS: There were no statistically significant differences (P ≥ 0.05) between sessions in both groups for all refractive variables (M, J0, and J45) and BCDVA. Spent time in refraction was reduced as the sessions went by (P < 0.05). The Eye Refract was more repeatable for refractive errors assessment in healthy subjects (M : S r = 0.27 D; J0 : S r = 0.09 D; J45 : S r = 0.06 D) compared to those with keratoconus (M : S r = 0.65 D; J0 : S r = 0.29 D; J45 : S r = 0.24 D), while it was similar for BCDVA. CONCLUSIONS: The Eye Refract offered better repeatability to assess refractive errors in healthy subjects compared to those with keratoconus. Despite measurements being also consistent in keratoconus subjects, they should be treated with caution in clinical practice.

Comparison of Two Wavefront Autorefractors: Binocular Open-Field versus Monocular Closed-Field.

PURPOSE: To evaluate the agreement and repeatability between a new commercially available binocular open-field wavefront autorefractor, as part of the Eye Refract system, and a monocular closed-field wavefront autorefractor (VX110). METHODS: A cross-sectional, randomized, and single-masked study was performed. Ninety-nine eyes of 99 healthy participants (37.22 ± 18.04 years, range 8 to 69 years) were randomly analyzed. Three measurements with the Eye Refract and the VX110 were taken on three different days, under noncycloplegic conditions. Mean spherical equivalent (MSE), cylindrical vectors (J0 and J45), and binocular corrected distance visual acuity (BCDVA) were compared between both autorefractors. An intersession repeatability analysis was done considering the values of repeatability (S r ) and its 95% limit (r). RESULTS: The VX110 showed more negative values (P < 0.001) in terms of MSE in comparison with the Eye Refract (0.20 D). Regarding cylindrical vectors, J45 showed statistically significant differences (P=0.001) between both wavefront autorefractors, but they were not clinically relevant (<0.05 D). In BCDVA, there were no statistically significant differences (P=0.667) between both wavefront autorefractors. Additionally, the Eye Refract was more repeatable than the VX110 in terms of both MSE (S r EYE REFRACT = 0.21 D, S r VX110 = 0.53 D) and J0 (S r EYE REFRACT = 0.12 D, S r VX110 = 0.35 D). CONCLUSIONS: The Eye Refract provided enough accuracy and reliability to estimate refractive errors in different age groups, achieving better results than the VX110. Therefore, the Eye Refract proved to be a useful autorefractor to be incorporated into clinical practice.

Corneal surface wettability and tear film stability before and after scleral lens wear.

PURPOSE: The aim of this study was to evaluate the anterior surface of scleral contact lens and ocular surface wettability before and after one-month of scleral lens wear in patients with keratoconus. METHODS: Forty-nine patients with keratoconus (36.26 ± 9.03 years) were recruited. The sample was divided into two groups: patients with intrastromal corneal ring (KCICRS group) and patients without ICRS (KC group). TFSQ, Schirmer I test, Ocular Surface Disease Index (OSDI questionnaire), tear break-up time (TBUT) and corneal staining were evaluated in two different visits: Baseline (before lens wear) and one-month visit (10 min after lens removal). Visual Analog Scale (VAS questionnaire) was filled in just after inserting the lenses and just before removing them. TFSQ mean and inferior were evaluated over the contact lens surface at the moment of inserting the lens (baseline visit) and after 8 h of lens wear (one-month visit). RESULTS: Anterior corneal surface TFSQ values increased in all groups after scleral lens wear (p < 0.05). However, there were no statistical differences found at the moment of inserting or after 8 h of lens wear on previous contact lens surface TFSQ (p > 0.05). No changes were found in tear volume for total and in KC and KCICRS groups (p > 0.05). For all groups, there was a statistical decrease of TBUT (p < 0.05). In addition, OSDI score, corneal staining and VAS score improved after scleral lens wear from baseline in total and in both KC and KCICRS groups (p < 0.05). CONCLUSION: The scleral contact lens surface keeps its wettability after one-month of wear. However, the wettability of the ocular surface is worse after contact lens wearing.

Signs and Symptoms of Dry Eye in Keratoconus Patients Before and After Intrastromal Corneal Rings Surgery.

PURPOSE: Based on the relationship between keratoconus and dry eye, the aim of this study was to evaluate changes in signs and symptoms of dry eye in keratoconus patients before and after intrastromal corneal ring surgery. METHODS: Fifteen keratoconus patients were enrolled in Fundación Jiménez-Díaz of Madrid and University Clinic of Optometry of the Universidad Complutense de Madrid (Madrid, Spain). Tear break up time (TBUT), Schirmer test without anesthesia, corneal staining, diadenosine tetraphosphate (Ap4A) concentration, and ocular surface disease index (OSDI) were evaluated. Impression cytology combined with laser confocal microscopy was performed to evaluate goblet cell density, mucin cloud height (MCH), and cell layer thickness (CLT). All measurements were performed before (pre) surgery, 1 month (post) and 6 months after surgery (post6m). RESULTS: We found no statistical differences in time in Schirmer test, TBUT, and corneal staining. OSDI scores were 44.96 ± 8.65, 26.30 ± 6.79, and 19.31 ± 4.28 for (pre), (post), and (post6m) surgery, respectively (p < 0.001). Impression cytology showed a decrease in cell density at (post6m) compared with presurgery (47.36 ± 35.15 cells/mm2 and 84.88 ± 32.08 cells/mm2, respectively, p = 0.04). At post6m, the MCH increased compared with presurgery values (13.97 ± 4.26 µm and 6.77 ± 2.51 µm, respectively, p < 0.001). There was a statistically significant increase in CLT in time. Ap4A tear concentrations were lower post6m than presurgery (1.02 ± 0.65 and 2.56 ± 1.10 µM, respectively, p < 0.001). CONCLUSION: Intrastromal corneal ring surgery induces changes improving dry eye symptoms but no changes were found in signs of dry eye after surgery in keratoconus patients except for the MCH that increases drastically. More studies are needed to clarify the reason of its improvement.

Comparison of Intraocular Pressure before and after Laser In Situ Keratomileusis Refractive Surgery Measured with Perkins Tonometry, Noncontact Tonometry, and Transpalpebral Tonometry.

Purpose. To compare the intraocular pressure (IOP) before and after Laser In Situ Keratomileusis (LASIK), measured by Diaton, Perkins, and noncontact air pulse tonometers. Methods. Fifty-seven patients with a mean age of 34.88 were scheduled for myopia LASIK treatment. Spherical equivalent refraction (SER), corneal curvature (K), and central corneal thickness (CCT) and superior corneal thickness (SCT) were obtained before and after LASIK surgery. IOP values before and after surgery were measured using Diaton, Perkins, and noncontact air pulse tonometers. Results. The IOP values before and after LASIK surgery using Perkins tonometer and air tonometers were statistically significant (p < 0.05). However, no significant differences were found (p > 0.05) for IOP values measured with Diaton tonometer. CCT decreases significantly after surgery (p < 0.05) but no statistical differences were found in SCT (p = 0.08). Correlations between pre- and postsurgery were found for all tonometers used, with p = 0.001 and r = 0.434 for the air pulse tonometer, p = 0.008 and r = 0.355 for Perkins, and p < 0.001 and r = 0.637 for Diaton. Conclusion. Transpalpebral tonometry may be useful for measuring postsurgery IOP after myopic LASIK ablation because this technique is not influenced by the treatment.