Background: Proper correction of spherical aberration using intraocular lenses requires precise selection of the sphericity of intraocular lens surfaces based on individual biometric data and corneal Asphericity coefficient (Q value). This study aimed to determine and analyze the corneal Q value and its related factors among Saudi participants. Methods: In this cross-sectional study, normal right eyes of healthy Saudi participants aged 17 – 58 years who visited Al-Kahhal Medical Complex, Dammam, Saudi Arabia, were included. The Pentacam rotating Scheimpflug camera was used to determine the average Q value at 6-mm diameter. Q values were obtained from each quadrant (superior, nasal, inferior, and temporal) and two meridians (horizontal and vertical). Mean Q values of the anterior and posterior corneal surfaces were also obtained. Other factors including age, sex, refractive error, and central corneal radius were documented. Results: Five hundred right eyes from 500 participants were included. The mean (standard deviation [SD]) (range) age was 27. 2 (7. 1) (18 – 58) years. The mean (SD) (range) Q value of 500 eyes was-0. 24 (0. 10) (-0. 71 to + 0. 09) anteriorly and-0. 16 (0. 14) (-0. 70 to + 0. 23) posteriorly, being significantly more prolate anteriorly (P < 0. 05). The corneas were significantly more prolate in the nasal than in the temporal quadrant, in the superior than in the inferior quadrant, and in the horizontal than in the vertical meridian (all P < 0. 05). There were statistically significant differences in anterior, nasal, temporal, inferior, horizontal, and vertical Q values among age groups (all P < 0. 05) but not in the superior or posterior Q values (both P > 0. 05). The corneas became less prolate with increasing age (P < 0. 05). However, Q values were comparable between the sexes (all P > 0. 05). There was no significant correlation between anterior (r = + 0. 08,P = 0. 095) or posterior (r =-0. 08,P = 0. 092) Q value and spherical equivalent, but a significant trend was detected toward more prolate shape with increasing myopia in the temporal and inferior quadrants (r = + 0. 19,P < 0. 001, r = + 0. 10,P = 0. 022, respectively). There was a significant negligible correlation between the posterior Q value and central corneal radius (r =-0. 18,P < 0. 001) but no significant correlation between the anterior Q value and central corneal radius (r = + 0. 02,P = 0. 673). Conclusions: Most corneas in this Saudi population were prolate in contour. Anterior corneal Asphericity was positively correlated with age and was not significantly related to sex, refractive error, or central corneal radius. Further studies are needed to verify our preliminary findings.

Purpose: To evaluate the effect of Asphericity and blue light filter (BLF) of three different intraocular lenses (IOLs) on the visual performance, second-and third-order aberrations (defocus, coma, trefoil), and contrast sensitivity after uneventful cataract surgery. Methods: One hundred and twenty eyes of 60 patients with clinically significant cataract were randomly assigned to receive one of the three IOL types: Bioline Yellow Accurate (aspheric, with BLF, i-medical, Germany), BioAcryl 60125 (spherical, without BLF, Biotech, France), and H65C/N (aspheric, without BLF, PhysIOL, Belgium). Each IOL was implanted in 40 eyes. Complete ophthalmologic examination, functional acuity contrast testing and wavefront analysis were performed 60 days postoperatively. Results: The mean postoperative best-corrected visual acuity (BCVA) was 0. 95 ± 0. 08, not differing statistically among the IOL groups (P = 0. 83). Mean defocus and coma values did not yield any statistically significant difference through the IOL groups varying from – 0. 784 to – 0. 614 μ m and 0. 129 to 0. 198 μ m (P = 0. 79 and 0. 34, respectively). Bioline Yellow Accurate IOL presented less trefoil aberrations, 0. 108 ± 0. 05 μ m, compared to the other two IOL types (BioAcryl [0. 206 ± 0. 19 μ m] and Physiol [0. 193 ± 0. 17 μ m], P < 0. 05). Contrast sensitivity values did not differ among the groups under all lighting conditions. Bioline Yellow IOL showed a statistically higher loss of contrast sensitivity (between mesopic and mesopic with glare conditions) compared to the BioAcryl and PhysIOL in 12 and 3 cpd spatial frequencies, respectively (P < 0. 05). Conclusion: Bioline Yellow IOL indicated lower contrast sensitivity under mesopic conditions when glare was applied but resulted in less trefoil aberrations after uneventful cataract surgery. No further differences were noted in postoperative visual performance among three IOL groups.

Purpose: To investigate the effect of the near visual task of movie-watching in the straight gaze position on corneal topographic parameters. Methods: Thirty myopic young adults with an average age of 25.10 ± 4.13 years were recruited for the study. The designed near visual task consisted of watching a movie in the straight gaze position at a distance of 40 cm for 30 minutes. Corneal topography was performed using Oculus Keratograph 4 (OCULUS, Wetzlar, Germany) before and immediately after watching the movie, as well as at 10, 20, and 30 minutes intervals after completing this near visual task. Zernike coefficients, Asphericity indices, refractive parameters, and diagnostic indices of keratoconus were recorded for statistical analysis. Results: Movie-watching at a close distance solely using the straight gaze position had no effect on Zernike coefficients (P > 0.130). Also, watching the movie had no effect on other corneal topography parameters including irregularities (P = 0.208), spherical eccentricity (P = 0.270), maximum decentration (P = 0.553), axis of maximum decentration (P = 0.186), peripheral astigmatism (P = 0.179), and average Asphericity of the quadrants at 10 to 30º (P > 0.163). Conclusion: The results of the present study showed that watching movies in the straight gaze position had no effect on corneal topographic parameters and did not cause errors in corneal topographic measurements.

Background: Many studies have used functional optical zone (FOZ) as a measure to compare different refractive laser treatment modalities. However, to our knowledge, no study has compared wavefrontoptimized (WFO) and wavefront-guided (WFG) laser in situ keratomileusis (LASIK) using FOZ. We compared the FOZ after WFO versus WFG LASIK in patients with myopia and myopic astigmatism. Methods: In this prospective comparative study, we included 100 myopic eyes of 50 patients with or without astigmatism. They were divided into two groups according to the platform used: WFO or WFG femtosecond LASIK. Using Holladay’, s equivalent keratometry reading (EKR) report of Pentacam HR, FOZ was defined as a zone centered on the pupil center with a standard deviation (SD) of 0. 5 D, around the mean EKR. The differences in FOZ between the two platforms were analyzed at 3 months postoperatively. Visual acuity, refractive error, corneal Asphericity (Q-value), and root mean square of higher-order aberrations (RMS for HOAs) were evaluated and compared. Results: The mean ±,SD of patient age was 26. 64 ±,5. 67 years. The preoperative characteristics of the two groups were comparable (all P > 0. 05). The intended optical zone (IOZ) was 6 mm in both groups. The mean laser ablation depth was significantly greater in the WFG group (18 µ, m per D) than in the WFO group (16 µ, m per D) (P = 0. 035). At 3 months postoperatively, the mean ±,SD of FOZ diameter was 4. 32 ±,0. 94 mm (71. 99 ±,15. 68% of intended optical zone) in the WFO group and 4. 16 ±,1. 13 mm (69. 33 ±,18. 78% of intended optical zone) in the WFG group, with no significant difference between the two groups (P = 0. 622). The change in corneal Asphericity was greater in the WFG group than in the WFO group (P = 0. 034). Postoperative mean corrected and uncorrected distance visual acuity, manifest refraction, and RMS for HOAs showed no significant difference between the two groups (all P > 0. 05). Conclusions: We found that WFG LASIK resulted in greater ablation depth and change in corneal Asphericity than WFO LASIK at 3 months postoperatively. However, there was no significant difference in FOZ diameter, refractive error, and RMS for HOAs between the two groups. Further research is needed to confirm these findings.

Purpose: To evaluate the multiple pretreatment characteristics and topographic factors of keratoconus (KC) patients and their relationship to clinical outcomes of corneal collagen cross‑ linking (CXL). Methods: In this prospective study, 61 patients (106 eyes) with KC as candidates for CXL were included. Demographic data including age, sex, place of birth and residence, atopic constitution, family history, rubbing history, sleep apnea, and blood group were collected via a structured checklist. Complete ophthalmologic examination and tear collection to assess tear interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α ) level were performed. Topometric parameters were evaluated using a rotating Scheimpflug topography device. Changes in best corrected visual acuity (BCVA) and maximum keratometry (K-max) were considered the main predicted variables. Predictive variables were analyzed by univariate and multivariate regression. Results: The use of multivariate analysis changes in K-max was significantly associated with rubbing frequency (coefficient = 0. 94, P = 0. 02), blood group (coefficient = 4. 52, P = 0. 005), pretreatment corneal Asphericity (coefficient = − 3. 99, P ≤ 0. 001), and pretreatment central keratoconus index (CKI) (coefficient = − 55. 38, P = 0. 001). Regarding the changes in BCVA, the multivariate analysis showed a significant association with place of birth (coefficient = − 0. 08, P = 0. 03), pretreatment BCVA (coefficient = − 0. 67, P < 0. 001), pretreatment central corneal thickness (CCT) (coefficient = − 0. 005, P = 0. 04), and pretreatment keratoconus index (KI) (coefficient = 0. 53, P = 0. 04). Other parameters assessed in the multivariable analysis did not appear to have an individual effect on treatment outcomes. Conclusion: Our results demonstrated that blood group, rubbing of eye, place of birth, corneal Asphericity, pretreatment BCVA, CKI, KI, and CCT were statistically associated with the outcome of KC following CXL.