Functional optical zone after wavefront-optimized versus wavefront-guided laser in situ keratomileusis

Elshawarby, Mariam A; Saad, Amr S; Helmy, Thanaa; Seleet, Mouamen M; El-Raggal, Tamer M.

doi:10.51329/mehdiophthal1431

Cited by 3 publications

(2 citation statements)

References 33 publications

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“…Average corneal asphericity has been calculated and analyzed in different populations, including those of China [ 2 , 3 , 8 , 9 , 13 ] , Egypt [ 14 ] , Germany [ 1 ] , the Netherlands [ 10 ] , India [ 15 ] , and the USA [ 5 , 7 , 16 ] . These studies used various topographers [ 3 , 7 , 8 , 10 , 15 ] , included different age groups, and had various sample sizes [ 3 , 7 , 8 , 10 , 15 ] ( Table 6 ).…”

Section: Discussionmentioning

confidence: 99%

Corneal asphericity and its related factors

Al-Somali,

Muhammad Abouollo,

Al-Jindan

et al. 2023

Med Hypothesis Discov Innov Ophthalmol

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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.

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Section: Discussionmentioning

confidence: 99%

Corneal asphericity and its related factors

Al-Somali,

Muhammad Abouollo,

Al-Jindan

et al. 2023

Med Hypothesis Discov Innov Ophthalmol

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“…Initially, biometry (ZEISS IOLMaster 500; Carl Zeiss Meditec AG, Jena, Germany) was used to calculate IOL power. The Pentacam Scheimpflug imaging system (Pentacam® HR; Oculus, Wetzlar, Germany) was used to measure the maximum keratometry (K1), minimum keratometry (K2), mean keratometry (Kmean) [ 13 ], and anterior chamber angle (ACA) [ 14 ].…”

Section: Methodsmentioning

confidence: 99%

Safety and efficacy of implantable phakic contact lens versus implantable collamer lens in myopia correction

Amer,

Ziada,

Fekry Elgazzar

et al. 2024

Med Hypothesis Discov Innov Ophthalmol

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Background: Phakic intraocular lenses (pIOLs) have proven to be excellent substitutes for excimer laser keratorefractive surgery in certain situations. We aimed to assess the efficacy and safety of two pIOLs, the implantable collamer lens (ICL V4c) versus the implantable phakic contact lens (IPCL V2), for myopic correction. Methods: In this prospective randomized clinical trial, we allocated eligible eyes with myopia > - 6 diopters into IPCL or ICL implantation groups, each including 100 eyes of 100 individuals. Preoperative and postoperative assessments at 3, 6, and 12 months included measurements of the spherical equivalent (SE), uncorrected distance visual acuity (UCDVA), best-corrected distance visual acuity (BCDVA), intraocular pressure (IOP), maximum keratometry (K1), minimum keratometry (K2), mean keratometry (Kmean), anterior chamber depth (ACD), anterior chamber angle (ACA), and endothelial cell density (ECD). Results: The groups had comparable demographic characteristics and baseline visual and anatomical values (all P > 0.05). The UCDVA, BCDVA, and SE of the two groups were comparable at baseline and at all postoperative follow-up examinations (all P > 0.05). Both groups experienced significant improvements in UCDVA, BCDVA, and SE at three months postoperatively (all P = 0.001), and measurements remained stable for up to 12 months. Keratometry readings were comparable between the groups over the follow-up period and remained unchanged at all visits (all P > 0.05). The ACA in the ICL group was significantly decreased at three months postoperatively (P = 0.001) and then widened significantly at 6 and 12 months (both P = 0.001). In the IPCL group, the postoperative ACA was significantly decreased at three months (P = 0.001) and was comparable to that in the ICL group (P > 0.01). However, at the 6- and 12-month postoperative visits, the ACA was significantly narrower in the IPCL group than in the ICL group (both P = 0.001). The ACD in both groups was decreased at three months postoperatively (both P = 0.001) and remained stable until the end of the study. The ECD remained comparable between the groups at all postoperative visits (all P > 0.05). We did not observe a significant ECD reduction in either group at any postoperative follow-up visit (all P > 0.05). We encountered no serious complications in either group. Conclusions: ICL and IPCL had comparable safety and efficacy outcomes in terms of anterior chamber morphometrics, visual and refractive results, and corneal parameters. Further multicenter randomized clinical trials with longer follow-up periods, larger sample sizes, and measurement of additional anterior chamber and corneal morphometrics, vault, and other vision parameters are needed to verify these findings.

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Effective optical zone: Differences between small-incision lenticule extraction and femtosecond LASIK for myopia

Çakır,

Yıldız

et al. 2024

Indian Journal of Ophthalmology

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Purpose: To compare the effective optical zones (EOZs) of small-incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (F-LASIK) by utilizing topographic methods on the tangential curvature difference map at postoperative 1 year and to identify parameters linked to the EOZ alterations following both surgeries. Methods: Myopic patients who underwent SMILE or F-LASIK were included in the study. Patients with refractive error greater than −9.0 D sphere or −0.50 D of astigmatism were excluded from the study. EOZs were measured at postoperative 1 year by using the tangential curvature difference map of the Scheimpflug tomography system. Correlations between the EOZ alterations and relevant parameters were assessed. Results: In total, 59 eyes in the SMILE group and 65 eyes in the F-LASIK group were assessed. The decrease in EOZ compared with the programmed optical zone was significantly higher in the F-LASIK group (P < 0.001). The increase in corneal asphericity was significantly relevant to the decrease in EOZin both groups according to the multiple regression analysis (P < 0.001, B/95% CI: 0.62/0.34 and 0.90, standardized-Beta: 0.587 for the SMILE group; P < 0.001, B/95% CI: 0.74/0.41 and 1.07, standardized-Beta: 0.631 for the F-LASIK group). Conclusion: The EOZ decreased 1 year after both SMILE and F-LASIK. The SMILE group showed less EOZ reduction than F-LASIK patients relative to the programmed optical zone. The decrease in EOZ was correlated with the increase in corneal asphericity in both groups.

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Functional optical zone after wavefront-optimized versus wavefront-guided laser in situ keratomileusis

Cited by 3 publications

References 33 publications

Corneal asphericity and its related factors

Corneal asphericity and its related factors

Safety and efficacy of implantable phakic contact lens versus implantable collamer lens in myopia correction

Effective optical zone: Differences between small-incision lenticule extraction and femtosecond LASIK for myopia

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