Efficacy of custom-made soft keratoconus lenses on corneal aberrations and photic phenomena in patients with keratoconus:a corneal topography imaging based study

AIM:To evaluate the efficacy of custom-made soft keratoconus(KC)lenses on corneal aberrations and photic phenomena in two different optical zones in patients with KC.METHODS:Sixty eyes of 42 patients with KC were examined at baseline and after fitting HydroCone(Toris K)soft silicone hydrogel lenses.Best spectacle-corrected visual acuity(BSCVA)and contact lens-corrected visual acuity(CLCVA)were recorded.Lower-and higher-order corneal aberrations(LOAs and HOAs)were measured with and without Toris K lenses and compared in central 4.5 mm and 7 mm zones.Mesopic pupil diameter and subjective photic phenomena were also assessed.RESULTS:Mean CLCVA was significantly improved compared to BSCVA(P<0.0001).Corneal curvature and refractive measurements were found to be significantly reduced by the use of Toris K lenses,except for posterior corneal curvature values.In the 4.5 mm central optical zone,all wavefront aberrations decreased significantly after lens fitting(P<0.0001).In contrast,in the 7 mm(peripheral)optical zone,values for HOAs,spherical and residual aberrations,and optical path differences were increased,while LOAs,trefoil,and quadrifoil coefficients were decreased.The rate of photic phenomena was significantly higher in participants with a pupil size>6.00 mm(85.7%).CONCLUSION:Toris K lenses provide good visual results and a significant reduction in central corneal aberrations in patients with KC but could cause an increase in peripheral aberrations.This practical and nonsurgical approach appears to be an effective method for the visual management of KC.

Optimal incision sites to reduce corneal aberration variations after small incision phacoemulsification cataract surgery

AIM： To analyze the effect of steep meridian small incision phacoemulsification cataract surgery on anterior,posterior and total corneal wavefront aberration.· METHODS： Steep meridian small incision phacoemulsification cataract surgery was performed in age-related cataract patients which were divided into three groups according to the incision site： 12 o＇clock, 9o＇clock and between 9 and 12 o＇clock（BENT） incision groups. The preoperative and 3-month postoperative root mean square（RMS） values of anterior, posterior and total corneal wavefront aberration including coma,spherical aberration, and total higher-order aberrations（HOAs）, were measured by Pentacam scheimpflug imaging. The mean preoperative and postoperative corneal wavefront aberrations were documented.·RESULTS： Total corneal aberration and total lower-order aberrations decreased significantly in three groups after operation. RMS value of total HOAs decreased significantly postoperatively in the 12 o＇clock incision group（P 〈0.001）. Corneal spherical aberration was statistically significantly lower after steep meridian small incision phacoemulsification cataract surgery in BENT incision group（P 〈0.05） and Pearson correlation analysisindicated that spherical aberration changes had no significant relationship with total astigmatism changes in all three corneal incision location.·CONCLUSION： Corneal incision of phacoemulsification cataract surgery can affect corneal wavefront aberration.The 12 o＇clock corneal incision eliminated more HOAs and the spherical aberrations decreased in BENT incision group obviously when we selected steep meridian small incision. Cataract lens replacement using wavefront-corrected intraocular lens combined with optimized corneal incision site would improve ocular aberration results.

One-year clinical efficacy evaluation of selective corneal wavefront aberration-guided FS-LASIK correction in patients with high myopia

AIM:To evaluate the effectiveness,safety,predictability,precision and changes of higher-order aberrations(HOAs)on corneal front surface of selective corneal wavefront aberration-guided femtosecond laser-assisted in situ keratomileusis(CW-FS-LASIK)in patients with high myopia 1-year postoperatively.METHODS:Totally 74 eyes of 37 patients with high myopia or myopic astigmatism in both the eyes who underwent the CW-FS-LASIK procedure in Xi’an Gaoxin Hospital from January 2021 to June 2021 were included.The changes of uncorrected distance visual acuity(UDVA),best corrected visual acuity(BCVA),spherical equivalent refraction(SER),astigmatism,HOAs and Strehl ratio(SR)on the anterior surface of the cornea after 1y of the surgery were analyzed.RESULTS:At postoperative 1y,the UDVA(logMAR)of 74 eyes(100%)reached 0 or better,including 0 in 8 eyes(10.81%),-0.1 in 45 eyes(60.81%),and-0.2 in 21 eyes(28.38%).The effectiveness index was 1.29±0.134.There was no decrease in postoperative BCVA compared with preoperative BCVA in all patients.Postoperative BCVA was the same in 44 eyes(59.46%)as preoperative BCVA,increased by 1 line in 23 eyes(31.08%)and increased by 2 lines in 7 eyes(9.46%)compared with preoperative BCVA.The safety index was 1.11±0.159.The estimated corrected SER before surgery was(-7.76±1.21)D,and the actual corrected SER was(-7.83±1.25)D(Y=0.9811X+0.2156,R2=0.9084).There was a high correlation between the estimated corrected SER and the actual corrected SER.The postoperative SER in 74 eyes(100%)was within±0.75 D.The postoperative astigmatism of all was within-0.75 D to 0.Root mean square(RMS)HOAs of spherical aberration and SR within 5 mm of the corneal front surface were all increased compared with those before operation(P<0.01).The total coma,horizontal coma and vertical coma were all decreased compared with those before operation(P<0.01).There was no statistically significant difference in horizontal trefoil and vertical trefoil compared with preoperative ones(P>0.05).CONCLUSION:Selective CW-FS-LASIK for correction of high myopia is effective,safe,predictive,and accurate.For patients with preoperative RMS HOAs over 0.25 defocus equivalent,postoperative coma aberration can be significantly reduced,and SR value can be increased,thus corneal imaging quality can be improved.

Evaluation of corneal parameter changes under different accommodative stimuli with Scheimpflug imaging-based tomography

AIM:To evaluate the reliability of measurements of corneal changes with accommodation in healthy eyes using a Scheimpflug imaging-based system and how these measurements distribute in the normal population.METHODS:Prospective,non-randomized,comparative study including 27 healthy subjects(54 eyes),including emmetropia(13 eyes),myopia(17 eyes),hyperopia(4 eyes)and astigmatism(20 eyes)groups.In all cases,a complete eye examination was performed,including the analysis of corneal changes with different accommodative stimuli(+2.00,0.00 and-3.00 D)using the Pentacam AXL system.The investigation was structured in 2 phases:repeatability analysis and characterization of accommodation-related corneal changes in healthy populations.RESULTS:In the repeatability analysis,the index of height asymmetry(IHA)showed the greatest variability with the three accommodative stimuli,being the results for the rest of parameters acceptable.The group of emmetropes showed significant differences with accommodative changes in the position of maximum keratometry(Kmax;P<0.05),whereas in the astigmatism group,significant changes were not only observed in the position of Kmax,but also in minimum corneal thickness(MCT),corneal spherical aberration,and total and low order aberration root mean square(all P<0.05).Likewise,a significant difference was found in the displacement of the X position of Kmax with+2.00 D and-3.00 D in the myopia group(P=0.033)as well as in changes with+2.00 D and-3.00 D in the magnitude of the position vector of Kmax in the emmetropia group(P<0.05).No significant changes were found between accommodative stimuli in the displacement of coordinates of MCT(P≥0.109).CONCLUSION:The position of Kmax and MCT in healthy corneas can change significantly when presenting different accommodative stimuli using the accommodation mode of the Pentacam system,with different trends in these accommodation-related corneal changes between refractive errors.Likewise,the consistency of the measurements obtained with Scheimpflug has been confirmed.

Changes in corneal curvature and aberrations after cataract surgery

Background:Surgically induced astigmatism(SIA)and corneal high-order aberrations(HOAs)are the two main causes of poor visual quality after cataract surgery.Changes in the parameters of corneal HOAs after cataract surgery and their effects on and relationships with changes in corneal curvature have not yet been reported.This study aimed to explore changes in anterior,posterior and total corneal curvature,astigmatism and HOAs after microincision cataract surgery.Methods:Sixty-one age-related cataract patients(61 eyes)were included in this prospective study.The total,anterior and posterior corneal astigmatism and corneal HOAs were analyzed by anterior segment optical coherence tomography(AS-OCT)and iTrace before,one day,one week and three months after 2.2 mm temporal microincision coaxial phacoemulsification to evaluate the changes in anterior,posterior and total corneal curvature,astigmatism and corneal HOAs.Results:The mean J0 and J45 values of anterior,posterior and total corneal curvature obtained by ASOCT showed no statistically significant difference between preoperatively and any postoperative followup.SIA occurred on the anterior,posterior and total corneal surfaces and showed no statistically significant difference at any postoperative follow-up.No significant changes in 3rd-order oblique trefoil,vertical coma or 4th-order spherical aberrations were observed after surgery except for a significant increase in horizontal coma at postoperative day 1(POD1).Conclusions:There were no significant changes in corneal curvature after 2.2 mm temporal microincision coaxial phacoemulsification,and the corneal HOAs were not changed significantly except for the increase in horizontal coma at POD1,which may be one of the main reasons of poor visual quality at POD1 in some cataract patients who have good uncorrected or corrected distance vision.

The early change of corneal vertical coma and trefoil in 2.8-mm superior incision cataract surgery

Background: To investigate early change of corneal aberrations after 2.8-mm superior incision phacoemulsification.Methods: This study comprised 80 eyes of 75 patients. All the patients underwent phacoemulsification with monofocal foldable intraocular lens(IOLs) implanted through a 2.8-mm superior corneal incision. The anterior corneal wavefront aberrations for the 6.0-mm pupillary diameter was measured by i Trace wavefront aberrometer(Tracey Technologies, Inc.) preoperatively and 1 month postoperatively. Changes of root mean square(RMS) values of Z(3,-3), Z(3, 3), Z(3,-1), Z(3, 1), and Z(4, 0) and total high order aberration(HOA) were evaluated.Results: The uncorrected and corrected visual acuities improve significantly(P<0.001). No significant postoperative changes were observed in spherical aberration(P=0.652). Significant changes in vertical coma and vertical trefoil(0.005±0.214 vs.-0.049±0.242, P=0.037;-0.141±0.222 vs.-0.258±0.359, P=0.001; separately). However, the total HOAs increased after cataract surgery(0.567±0.161 vs. 0.688±0.343, P<0.001).Conclusions: Corneal vertical coma and vertical trefoil changes significantly in 2.8mm superior corneal incision phacoemulsification cataract surgery. In addition, those had a trend to negative direction.

Ocular higher-order aberrations and mesopic pupil size in individuals screened for refractive surgery

AIM: To study the distribution of ocular higher-order aberrations(HOAs) and mesopic pupil size in individuals screened for refractive surgery. · METHODS: Ocular HOAs and mesopic pupil size were studied in 2 458 eyes of 1 240 patients with myopia, myopic astigmatism and compound myopic astigmatism and 215 eyes of 110 patients with hyperopia, hyperopic astigmatism and compound hyperopic astigmatism using the Zywave aberrometer (Busch& Lomb). All patients had correctable refractive errors without a history of refractive surgery or underlying diseases. Root-mean-square values of HOAs, total spherical aberration, total coma and mesopic pupil size were analyzed. Ocular HOAs were measured across a ≥ 6.0 mm pupil, and pupil size measurements were performed under the mesopic condition. · RESULTS: The mean values of HOAs, total spherical aberration and total coma in the myopic group were 0.369 μm, ±0.233, 0.133±0.112μm and 0.330±0.188μm, respectively. In the hyperopic group the mean values of HOAs, total spherical aberration and total coma were 0.418μm±0.214, 0.202±0.209μm and 0.343±0.201μm, respectively. Hyperopes showed greater total HOAs (P <0.01) and total spherical aberration (P <0.01) compared to myopes. In age-matched analysis, only the amount of total spherical aberration was higher in the hyperopic group (P =0.05). Mesopic pupil size in the myopic group was larger (P ≤0.05). · CONCLUSION: The results suggested that significant levels of HOAs were found in both groups which are important for planning refractive surgeries on Iranians. There were significantly higher levels of total spherical aberration in hyperopes compared to myopes. Mesopic pupil size was larger in myopic group.

Effects of rigid gas permeable contact lens on morphological parameters and vision-related quality of life in keratoconus patients

AIM: To evaluate the effect of rigid gas permeable contact lens(RGP-CL) on corneal morphological parameters and vision-related quality of life in keratoconus(KC) patients.METHODS: Totally 57 eyes of 30 KC patients who were followed-up for more than two years, including 17 RGP wearers(32 eyes) and 13 non-wearers(25 eyes) were retrospectively analyzed. Initial medical history and corneal topography were collected at baseline. Corneal topography, corneal aberration, optical coherence tomography, and vision-related quality of life questionnaires were performed at the last follow-up.RESULTS: According to corneal topography, increase of the flattest keratometric values was higher in RGP wearers than in non-wearers(P=0.038). The morphological parameters, including symmetry index of front corneal curvature(P=0.004) and Baiocchi-Calossi-Versaci index front(P=0.047), were lower in RGP wearers than in nonwearers. Vertical coma was smaller in RGP wearers than non-wearers in 3.0, 5.0, 6.0, and 7.0 mm pupil diameters, respectively(P<0.05). The environmental triggering domain of ocular surface disease index was worse in RGP wearers as compared to non-wearers(P=0.003). At the last followup, there were no significant differences in constituent ratios of KC progression, corneal thickness topography, epithelial thickness topography, morphological parameters of corneal topography, and other questionnaire scores between the two groups(all P>0.05).CONCLUSION: Long-term use of RGP does not worsen KC but may cause corneal epithelial remodeling to increase symmetry of corneal anterior surface, reduce corneal vertical coma and improve visual quality. However, RGP wearing causes a slight decrease in vision-related quality of life. The occurrence of ocular surface symptoms is mainly associated with environmental triggering factors.

Correlation between visual function and refractive,topographic, pachymetric and aberrometric data in eyes with keratoconus

AIMTo analyze the relationship between two visual functions and refractive, topographic, pachymetric and aberrometric indicators in eyes with keratoconus.METHODSCorrected distance visual acuity (CDVA), and letter contrast sensitivity (CS) were correlated with refraction, corneal topography, pachymetry, and total corneal wavefront data prospectively in 71 eyes with keratoconus. The topographic indices assessed were simulated keratometry for the flattest and steepest meridians (SimK1 and SimK2), posterior steeper K (Ks), elevation value in best-fit sphere (BFS) maps, squared eccentricity (Є2), aspheric asymmetric index (AAI), pachymetry, thickness progression index (TPI), the amount of pachymetric decentralization (APD), and GalileiTM-keratoconus indices.RESULTSThe mean CDVA (expressed as logMAR) were 0.25±0.21. The mean CS was 1.25±0.46. The spherical refraction correlated well with CDVA (r=-0.526, P<0.001). From topographic indices, SRI correlated with CS (r=-0.695), and IAI with CS (r=-0.672) (P<0.001 for all). Root mean square (RMS) was 4.3±1.81 µm, spherical aberration (SA) was -0.4±0.67 µm, vertical and horizontal coma were -2.1±1.47 and -0.4±0.72 µm. All wavefront data (except horizontal coma), AAI, Є2 and maximum BFS correlated significantly with the visual function (P≤0.001 for all).CONCLUSIONIn this study, CS is more affected than CDVA as a visual function. The quantity and quality of vision is significantly correlated with well-known and new topographic indices. There is not a significant correlation between visual function and pachymetric parameters. The significantly correlated indices can be used in staging keratoconus and to follow the outcome of a treatment.

Clinical study of customized aspherical intraocular lens implants

AIM:To compare if there is an improvement in visual functions with age-related cataracts between patients receiving a aspherical intraocular lens(IOL) based on corneal wavefront aberration and patients randomly assigned lenses.METHODS:A total of 124 eyes of 124 patients with age-related cataracts were placed in experimental group and a group receiving randomly assigned(RA) lenses.The experimental group was undergone Pentacam corneal spherical aberration measurement before surgery; the targeted range for residual total spherical aberration after surgery was set to 0-0.3 μm. Patients with a corneal spherical aberration 【0.3 μm were implanted with a zero-spherical aberration advanced optics(AO) aspherical IOL and patients with an aberration ≥0.3 μm received a Tecnis Z9003 aspherical lens in experimental group. RA patients were randomly implanted with an AO lens or a Tecnis Z9003 lens. Three months after surgery total spherical aberration, photopic/mesopic contrast sensitivities, photopic/mesopic with glare contrast sensitivities, and logMAR vision were measured.RESULTS:Statistical analysis on logMAR vision showed no significant difference between two groups(P =0.413). The post-surgical total spherical aberration was 0.126 ±0.097 μm and 0.152 ±0.151 μm in the experimental and RA groups, respectively(P =0.12). The mesopic contrast sensitivities at spatial frequencies of 6,12 and 18 c/d in the experimental group were significantly higher than of the RA group(P =0.00; P =0.04;P =0.02). The mesopic with glare contrast sensitivity in the experimental group at a spatial frequency of 18 c/d was also significantly higher vs the RA group(P =0.01).CONCLUSION:Pre-surgical corneal spherical aberration measurement in cataract patients followed bycustomized selection of aspherical IOL implants improved mesopic contrast sensitivities at high spatial frequencies, and thus is a superior strategy compared to the random selection of aspherical intraocular lens implants.

Artificial neural network to guide intracorneal ring segments implantation for keratoconus treatment:a pilot study

Background:To analyze the clinical results of an artificial neural network(ANN)that has been processed in order to improve the predictability of intracorneal ring segments(ICRS)implantation in keratoconus.Methods:This retrospective,comparative,nonrandomized,pilot,clinical study included a cohort of 20 keratoconic eyes implanted with intracorneal ring segments KeraRing(Mediphacos,Belo Horizonte,Brazil)using the ANN(ANN group)and 20 keratoconic eyes implanted with KeraRing using the manufacturer’s nomograms(nomogram group).Uncorrected distance visual acuity(UDVA),corrected distance visual acuity(CDVA)(visual acuity is expressed in decimal value and in LogMAR value in brackets),manifest refraction,corneal topography,tomography,aberrometry,pachymetry and volume analysis(Sirius System.CSO,Firenze,Italy)were performed during the preoperative visit;and the two groups,ANN group and nomogram group,did not differ significantly preoperatively in all of the parameters evaluated.These preoperative values were compared with the results obtained at the third-month visit.Mann-Whitney test and Wilcoxon test were used for the statistical analyses.Results:The spherical equivalent and the keratometric values decreased significantly in both groups.The CDVA improved from 0.60±0.23(0.22 LogMAR)pre-operatively to 0.73±0.21(0.14 LogMAR)post-operatively in the ANN group(p<0.005),and from 0.54±0.19(0.27 LogMAR)pre-operatively to 0.62±0.19(0.21 LogMAR)post-operatively in the nomogram group(p<0.01),with statistically significant difference between the two groups(p<0.05),being better in the ANN group.Coma-like aberrations decreased significantly in the ANN group,while in the nomogram group they did not change significantly,but no statistically significant difference was found between the two groups.Conclusions:ANN to guide ICRS provides an increase in the visual acuity,reduction in the spherical equivalent and improvement in the optical quality of keratoconus patients.ANN gives better results when compared with the manufacturer’s nomograms in terms of better corrected vision and reduction of the coma-like aberrations.The constant inclusion of new cases will make the predictability of ANN increasingly better as the software finetunes its learning.

Artificial neural network to guide intracorneal ring segments implantation for keratoconus treatment:a pilot study

Background:To analyze the clinical results of an artificial neural network(ANN)that has been processed in order to improve the predictability of intracorneal ring segments(ICRS)implantation in keratoconus.Methods:This retrospective,comparative,nonrandomized,pilot,clinical study included a cohort of 20 keratoconic eyes implanted with intracorneal ring segments KeraRing(Mediphacos,Belo Horizonte,Brazil)using the ANN(ANN group)and 20 keratoconic eyes implanted with KeraRing using the manufacturer's nomograms(nomogram group).Uncorrected distance visual acuity(UDVA),corrected distance visual acuity(CDVA)(visual acuity is expressed in decimal value and in logMAR value in brackets),manifest refraction,corneal topography,tomography,aberrometry,pachymetry and volume analysis(Sirius System,CSO,Firenze,Italy)were performed during the preoperative visit;and the two groups,ANN group and nomogram group,did not differ significantly preoperatively in all of the parameters evaluated.These preoperative values were compared with the results obtained at the third-month visit.Mann-Whitney test and Wilcox on test were used for the statistical analyses.Results:The spherical equivalent and the keratometric values decreased significantly in both groups.The CDVA improved from 0.60±0.23(0.22 logMAR)preoperatively to 0.73±0.21(0.14 logMAR)postoperatively in the ANN group(P<0.005),and from 0.54±0.19(0.27 logMAR)preoperatively to 0.62±0.19(0.21 logMAR)postoperatively in the nomogram group(P<0.01),with statistically significant difference between the two groups(P<0.05),being better in the ANN group.Coma-like aberrations decreased significantly in the ANN group,while in the nomogram group they did not change significantly,but no statistically significant difference was found between the two groups.Con elusions:ANN to guide ICRS provides an increase in the visual acuity,reduction in the spherical equivalent and improvement in the optical quality of keratoconus patients.ANN gives better results when compared with the manu facturer's no mograms in terms of better corrected vision and reduction of the coma-like aberrations.The constant inclusion of new cases will make the predictability of ANN increasingly better as the software finetunes its learning.