Mean Keratometric Readings Research Articles

Keratometric Outcomes after Simultaneous versus Sequential Intracorneal Ring Segment Implantation with Femtosecond Laser and Corneal Collagen Crosslinking in Egyptian Patients with Keratoconus and Ectasia.

Keratoconus (KC) is degenerative corneal disorder, with central and paracentral thinning and corneal ectasia. For KC progressive cases, primary treatment included corneal collagen cross linking (CXL) to stabilize coning and intracorneal rings segment (ICRS) to correct visual acuity. The aim of the study is to assess efficacy and safety of ICRS and CXL on one session (Simultaneous) or two sessions (sequential) with maximum of 1 month apart. This Prospective Intervention Comparative research made at Armed forces hospital, Cairo, Egypt from January 2017 to December 2019. Forty patients (60 eyes) with mild to moderate KC were enrolled. Patients sorted into Simultaneous group includes 21 patients (30 eyes) undergo two procedures (ICRS then CXL) at the same session and Sequential group included 19 patients (30 eyes) undergo ICRS then CXL on two sessions with month apart. Patients followed up at end of 1st, 3rd, and 6th months. Assessment included changes in corrected corneal surface irregularities as minimum keratometric 1 (K1), maximum keratometric readings (K2), and mean keratometric (Km) readings. Improvement of K1, K2, and Km in Simulations and Sequential groups achieved at end of 1st-, 3rd-, and 6th-month postoperative versus preoperative. Maximum improvement in Simulations and Sequential groups in K1 achieved at end of 6th and 1st months, in K2 at end of 3rd and 6th months and in Km at end of 1st and 3rd months. Combined ICRS and CXL act safely in one or two sessions and there are no statistically significant variations between results on both methods in keratometric readings.

Reversal of Myopic Correction for Patients Intolerant to LASIK

Purpose To evaluate the outcome of the reversal of myopia correction in patients intolerant to LASIK. Methods This study is a retrospective and case series of patients who decided to reverse their previous myopic LASIK correction between July 2012 and July 2020. It was conducted at a private refractive surgery centre, Ismailia, Egypt. The patients were followed up after reversal treatment for one year. Primary LASIK and reversal treatment were performed by a 500 kHz Amaris excimer laser platform. The main outcomes included refractive predictability, stability, efficacy, and safety and any reported complications. Results This study included 48 eyes of 24 patients (6 male and 18 female patients). The average duration between the primary LASIK surgery and reversal treatment was 3.20 ± 0.30 months (range 3 to 4 months). Reversal treatment was bilateral in all patients. The mean age of the patients was 38 ± 1.9 years (range 37 to 45 yrs). After reversal, the mean postreversal cycloplegic refraction spherical equivalent was −1.82 ± 0.34 D (range −1.50 to −3.00 D). The mean ablation depth was 34.10 ± 7.36 μm (range 20 to 46 μm), and the mean of the central corneal thickness 12 months after reversal treatment was 510.2 ± 14.4 μm (range 515 to 487 μm). The mean keratometric reading was 42.6 ± 1.6 (range 42.5 to 44.8). The mean of CDVA was 0.2 ± 0.03 log MAR (range −0.10 to 0.4 log MAR). The mean optical zone of reversal treatment was 6.1 ± 0.3 mm (range 5.9 to 6.2 mm). UDVA was 0.4 log MAR in 87.5% of the patients, 0.5 log MAR in 8.3% of the patients, and 0.6 log MAR in 4.2% of the patients. CDVA remained unchanged in 83.3% of patients; 2.1% of the patients gained one line of CDVA (Snellen); 8.3% of the patients lost one line of CDVA; 6.3% of the patients lost two lines of CDVA. No cases of corneal ectasia were recorded. The only postoperative complications were flap microfolds in 3 eyes (6.25%). Conclusion In conclusion, this study demonstrates that reversal of myopic LASIK treatment is a safe, stable, and effective option for intolerant patients.

Visual Outcomes After Implantation of Allogenic Lenticule in a 100-µm Pocket for Moderate to High Hyperopia: 2-Year Results.

To investigate 2-year visual outcomes, stability, and predictability after allogenic lenticule implantation in a 100-µm pocket for moderate to high hyperopia correction. In this prospective case series, 14 eyes of 9 patients with moderate to high hyperopia ranging from +3.00 to +8.00 diopters sphere were included between March and September 2018. Allogenic lenticules extracted from myopic small incision lenticule extraction were implanted into a pocket created by femtosecond laser at a 100-µm depth in recipients with hyperopia. All patients were followed up for 2 years. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity, manifest refraction, corneal topography, Fourier-domain optical coherence tomography, and in vivo confocal microscopy were examined. At postoperative 2 years, 2 eyes (14.3%) gained one line of CDVA, 11 eyes (78.6%) had unchanged CDVA, and 1 eye (7.1%) lost one line of CDVA. No eyes lost two or more lines of CDVA. Twelve of the treated eyes (85.7%) had postoperative uncorrected near visual acuity equal to or better than pre-operative values. The spherical equivalent decreased from +5.53 ± 1.45 D preoperatively to -0.60 ± 1.20 D at postoperative year 2 (P < .001). The anterior mean keratometric readings increased from 42.41 ± 1.03 D preoperatively to 48.38 ± 1.98 D at postoperative year 2 (P < .001). Of 14 treated eyes, 10 eyes (71.4%) had spherical equivalent within ±1.00 D. The findings suggest that allogenic lenticule transplantation may be a promising option for the correction of moderate to high hyperopia. [J Refract Surg. 2021;37(11):734-740.].

Aberrometric, Keratometric, and Visual Outcomes After Trans-Epithelial Topography-Guided Phototherapeutic Keratectomy for the Treatment of Irregular Corneas.

PurposeTo assess the safety, aberrometric and keratometric changes, and stability of trans-epithelial topography-guided phototherapeutic keratectomy (TE-TG-PTK) with mitomycin C (MMC) using the ALLEGRO Topolyzer platform for the treatment of irregular astigmatism.MethodsThis is a retrospective case series including 57 eyes that underwent TE-TG-PTK + MMC using the ALLEGRO Topolyzer platform for the treatment of irregular astigmatism. CDVA, manifest refraction (MR), keratometry readings, and aberrometry readings were analyzed at 1, 3, 6, and 12 months.ResultsCauses of corneal irregularity included non-infectious leucoma (n=23), infectious leucoma (n=7), adenoviral keratitis (n=20), corneal haze (n=2), post-penetrant keratoplasty (PKP) (n=1), and others (n=4). Overall, 76% of the eyes (n=40) gained lines of vision; patients gained 1, and 2 or more lines of vision in 76%, and 38% of cases, respectively. Only 1 patient (2%) lost 5 lines of vision. Mean preoperative CDVA (LogMAR) was 0.37 ±0.31 and improved to 0.14 ±0.18 (p<0.001) at final follow-up (12 months). CDVA remained unchanged in 10 eyes (21%). No significant changes were observed in mean keratometry (Kmean) and keratometric astigmatism readings. Regarding aberrometry, only changes in coma proved to be significant 6 months after surgery (P<0.01). No intraoperative/postoperative complications were reported.ConclusionAt final follow-up, significant improvements were observed in CDVA and coma. TE-TG-PTK + MMC proved to be an effective and safe procedure for the treatment of corneal irregular astigmatism due to several causes.

Inter-device measurement variability of vital data parameters for keratorefractive and cataract refractive surgery.

Introduction:The measurements of corneal white-to-white (WTW) diameter and pupil size are critical for decision making in refractive surgery. Currently, automatic measurement of keratometry, corneal WTW, and pupil size are implemented in several ocular devices. The purpose of this study was to examine the agreement between two commonly used devices, an autorefractor and an optical biometer, for these parameters.Methods:Measurements were performed with both a Lenstar LS-900 and Nidek ARK-1 by an experienced examiner in random order. The devices were placed in close proximity within the same dimly lit room.Results:The measurements of 65 right eyes were analyzed. The results of the flat, steep, and mean keratometric reading were not significantly different (p = 0.96, p = 0.90, p = 0.93, respectively). Corneal WTW distances showed only moderate agreement between devices and were found to be significantly different (r = 0.8071; p < 0.01). Pupil diameters showed poor agreement between devices and were significantly different (r = 0.4890; p < 0.01). Agreement between implantable contact lens sizing, based on the measurements obtained by the two devices, was achieved for 19 of the 51 eyes (37.3%).Conclusion:We found a significant difference in WTW and pupil size measurements between ARK-1 and Lenstar. Results for both of the devices cannot be considered interchangeable for these data parameters.

Analysis of Keratometric Readings and Astigmatism in Different Grades of Pterygium at Muhimbili National Hospital

Pterygium is a worldwide disease affecting people of all races especially in tropical and sub-tropical areas. It has a direct effect on corneal curvature leading to visual impairment in the form of astigmatism especially in advanced grades. Surgical removal is the treatment of choice for a progressive pterygium. However, recurrence of pterygium after surgical removal discourages surgical intervention during early stages of the disease. Reports from literature show that encroachment of the cornea by a progressive pterygium causes astigmatism with resultant visual loss even before a pterygium obscures the visual axis. Furthermore, the grade of pterygium is related to keratometric readings and the amount of astigmatism. Knowing the grades of pterygium that are associated with changes in corneal dioptric power and astigmatism can emphasize the fact that astigmatism is an indication for surgical removal of a pterygium before visual impairment occurs. The objective of the study was to determine and analyze the keratometric readings and astigmatism in different grades of pterygium. A cross-sectional descriptive study was conducted in adult eye clinic at Muhimbili National Hospital between June and December 2019 after Ethical approval from the Research and Publication Committees of Muhimbili University of Health and Allied Sciences and the executive director of Muhimbili National Hospital. Consecutive sampling of 64 patients with pterygium was done. Recruited patients was underwent a short history and ophthalmological examination for assessment of the size of pterygium by using slit lamp bio microscopy. Auto refractometry and Keratometry were performed. 34 (53%) were females. 48% were aged between 41 to 50 years with a mean age of 45.14+/- 9.93(SD) years. 34(27.4%) eyes had grade one, 41(33%) had grade two, 28(22.6%) eyes grade 3 and 21(17%) eyes with grade four pterygia. The mean keratometric reading for the vertical (K1) and horizontal meridian (K2) were 43.05D and 44.16D respectively. 79.5% eyes with grade 3 and 4 pterygia presented with astigmatism of more than 1D. The overall mean magnitude of astigmatism was 1.429DC +/- 0.6225SD. This study results show that the keratometric readings and magnitude of astigmatism increased with increasing size of pterygium with a positive correlation of r=0.922 r=0.786 respectively.

Regional comparison of preoperative biometry for cataract surgery between two domestic institutions.

Regional variations of the preoperative biometry can affect the refractive accuracy of cataract surgery. We aimed to compare the preoperative biometric data for cataract surgery between two domestic institutions. We retrospectively reviewed the preoperative biometric data of 673 consecutive eyes undergoing standard cataract surgery at Miyata Eye Hospital (Miyazaki; M group) and Kitasato University Hospital (Kanagawa; K group), and compared these data between the two groups. We found significant differences in the mean keratometric readings (44.39 ± 1.56D vs. 44.09 ± 1.74D) (unpaired t test, p = 0.034), the anterior chamber depth (3.14 ± 0.43mm vs. 3.46 ± 0.62mm) (p < 0.001), the axial length (23.98 ± 1.62mm vs. 24.59 ± 1.82mm) (p < 0.001), and the lens thickness (4.64 ± 0.48mm vs. 4.37 ± 0.62mm) (p < 0.001), in the M and K groups, respectively. Otherwise, we found no significant differences in corneal astigmatism (p = 0.104), or central corneal thickness (p = 0.480) between the two groups. For subgroup analysis, the prediction error (0.06 ± 0.47D) in the M group was significantly more hyperopic than that (- 0.09 ± 0.54D) in the K group (p = 0.006). There were significant differences in the mean keratometric readings, the anterior chamber depth, the axial length, and the lens thickness, by approximately 0.3D, 0.3mm, 0.6mm, and 0.3mm, respectively. Regional variations of the preoperative biometry did exist to some extent, and were not clinically negligible, in consideration of the precise IOL power calculation and the subsequent refractive accuracy of cataract surgery. University Hospital Medical Information Network Clinical Trial Registry (000037994).

Pediatric versus Adult Corneal Collagen Crosslinking: Long-term Visual, Refractive, Tomographic and Aberrometric Outcomes

ABSTRACT Purpose To comparatively evaluate the long-term visual, refractive, topographic and aberrometric outcomes of conventional corneal collagen crosslinking (CXL) in the management of pediatric versus adult progressive keratoconus patients. Materials and Methods Retrospective, cross-sectional review of consecutive progressive keratoconus cases of corneal standard CXL using a standardized protocol for treatment and examinations was performed. Best spectacle-corrected distance visual acuity (CDVA), manifest refraction, slit lamp biomicroscopy, corneal tomography, corneal aberrometry and endothelial cell counts were evaluated at baseline and yearly at all postoperative follow-up examinations after month-12. The outcomes were analyzed by dividing the patients into 2 age groups; pediatric (≤18 years) versus adult (>18 years). Results Eighty-eight eyes (54 patients) in the pediatric and 104 eyes (68 patients) in the adult age groups completed 3 years follow-up. Compared to baseline, the mean CDVA, manifest refraction, keratometric readings, tomographic and aberrometric parameters improved statistically significantly in both groups at postoperative year-3 and year-4, without any statistically significant between-group differences. No change in the mean endothelial cell density (p > .05), or no sight threating complication was encountered in any patient eye in either group. In a subset of patients who were followed for 4 years (71 eyes in the pediatric and 70 eyes in the adult age groups), the outcome analyses were again similar between-groups. Conclusion Conventional corneal CXL effectively halts the progression of keratoconus in both pediatric and adult age groups in long-term follow-up with similar visual, refractive, tomographic and aberrometric efficacy in both groups.

Visual Acuity, Rafraction, And K Reading Changes After Five Versus Six Millimeters Optical Diameter Intracorneal Ring Segments For Treatment Of Keratoconus

Purpose: To evaluate changes in visual acuity, refraction, and keratometric (K) readings after implantation of five millimeters versus six millimeters optical diameter of intracorneal ring segments (ICR) for treatment of keratoconus grade (2-4). Patients and methods: A prospective nonrandomized clinical comparative study. Thirty four eyes were included in this study. They were classified into two groups: Group I: Seventeen eyes of patients with Keratoconus grades (2-4) were subjected to 5 mm optical diameter intracorneal ring implantation. Group II: Seventeen eyes of patient with keratoconus grade (2-4)were subjected to 6 mm optical diameter intracorneal ring implantation. Results: Thirty four eyes of 22 patients (9 males and 13 females) with keratoconus grade (2-4) were enrolled in this study. The mean age + SD of the patients in group I was 26.36 ± 7.06 years and in group II was 23.09 ± 6.92 years. The mean keratometric (K) reading decreased from 50.05 ± 3.64D. to 46.96 ± 4.42D in group I and from50.48 ± 5.18D to 46.91 ± 5.44D in group II. There was a statistically significant improvement in the postoperative uncorrected distance visual acuity, corrected distance visual acuity, K readings, manifest spherical and cylindrical refractive errors, and spherical equivalent in both groups. No serious intraoperative complications were reported. Conclusion: Both 5mm and 6mm ICR improve significantly UCVA, BCVA, decreased the corneal power and corneal astigmatism but 6 mm showed significant improvement in cylindrical errors and BCVA compared to 5 mm ICR.

Visual Acuity, Rafraction, And K Reading Changes After Five Versus Six Millimeters Optical Diameter Intracorneal Ring Segments For Treatment Of Keratoconus

Purpose: To evaluate changes in visual acuity, refraction, and keratometric (K) readings after implantation of five millimeters versus six millimeters optical diameter of intracorneal ring segments (ICR) for treatment of keratoconus grade (2-4). Patients and methods: A prospective nonrandomized clinical comparative study. Thirty four eyes were included in this study. They were classified into two groups: Group I: Seventeen eyes of patients with Keratoconus grades (2-4) were subjected to 5 mm optical diameter intracorneal ring implantation. Group II: Seventeen eyes of patient with keratoconus grade (2-4)were subjected to 6 mm optical diameter intracorneal ring implantation. Results: Thirty four eyes of 22 patients (9 males and 13 females) with keratoconus grade (2-4) were enrolled in this study. The mean age + SD of the patients in group I was 26.36 ± 7.06 years and in group II was 23.09 ± 6.92 years. The mean keratometric (K) reading decreased from 50.05 ± 3.64D. to 46.96 ± 4.42D in group I and from50.48 ± 5.18D to 46.91 ± 5.44D in group II. There was a statistically significant improvement in the postoperative uncorrected distance visual acuity, corrected distance visual acuity, K readings, manifest spherical and cylindrical refractive errors, and spherical equivalent in both groups. No serious intraoperative complications were reported. Conclusion: Both 5mm and 6mm ICR improve significantly UCVA, BCVA, decreased the corneal power and corneal astigmatism but 6 mm showed significant improvement in cylindrical errors and BCVA compared to 5 mm ICR.

Simultaneous intratunnel cross-linking with intrastromal corneal ring segment implantation versus simultaneous epithelium-off cross-linking with intrastromal corneal ring segment implantation for keratoconus management.

PurposeThe purpose of this study is to compare the efficacy of intratunnel cross-linking combined with intrastromal corneal ring segment (ICRS) implantation versus combined epithelium-off (epi-off) cross-linking and ICRS implantation for the management of keratoconus.MethodsOur study included 20 eyes of 12 patients with moderate-to-severe keratoconus. Group A included 10 eyes that underwent simultaneous ICRS implantation with intratunnel cross-linking. Group B included 10 eyes that underwent simultaneous ICRS implantation with epi-off cross-linking. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest sphere and cylinder, mean and maximum keratometric readings, corneal thickness at pachy apex and thinnest location, as well as corneal hysteresis (CH) and corneal resistance factor (CRF) were compared preoperatively and at 6 months postoperatively.ResultsThe mean UDVA and CDVA improved significantly in both groups with a statistically nonsignificant difference between the groups (P=0.798 and 0.126, respectively). The manifest cylinder decreased significantly in both groups, while the manifest sphere decreased significantly in Group A but nonsignificantly in Group B with a statistically nonsignificant difference between the groups (P=0.773 and 0.111, respectively). Both techniques led to significant flattening of the cornea and a significant decrease of Km and Kmax with a statistically nonsignificant difference between the groups (P=0.312 and 0.857, respectively). There was a statistically significant decrease in CH in both groups postoperatively; however, there was a statistically nonsignificant increase in CRF after both techniques with a statistically nonsignificant difference between the groups in the mean change of CH and CRF (P=0.633 and 0.313, respectively). No intraoperative or postoperative complications were observed in both groups.ConclusionBoth techniques improved the visual and refractive outcomes in cases of moderate and severe keratoconus with no statistically significant difference between the groups; however, simultaneous intratunnel cross-linking and ICRS implantation showed early visual rehabilitation due to the absence of epithelial defect.

Myoring and Ferrara ring segment implantation using femtosecond laser for treatment of keratoconus

Purpose To compare visual acuity, refraction, and topographic corneal changes after implantation of a MyoRing versus Ferrara ring segment for management of keratoconus. Patients and methods This is a prospective nonrandomized clinical comparative study. Forty eyes of 25 patients with keratoconus grades 2–4 were included in the study and were divided into two groups: group A (MyoRing group) included 20 eyes of patients with keratoconus subjected to femtosecond laser-assisted MyoRing implantation and group B included 20 eyes of patients with keratoconus subjected to femtosecond laser-assisted Ferrara ring segment implantation. Results Forty eyes of 25 patients (12 males and 13 females) with keratoconus grades 2–4 were enrolled in this study. The mean age of the patients in group A was 26.62±6.18 years and in group B was 24.72±5.06 years. The mean central corneal thickness improved from 440.25 to 476.57 µm in group A and from 441.35 to 470.63 μm in group B. The mean keratometric (K) reading decreased from 49.97±14.26 to 44.55±2.16 D in group A and from 48.69+4.26 to 44.85±1.92 D in group B. There was a statistically significant improvement in the postoperative uncorrected distance visual acuity, corrected distance visual acuity, K readings, manifest spherical and cylindrical refractive errors, and spherical equivalent in both groups. No serious intraoperative complications were reported. Conclusion Both MyoRing and Ferrara ring segments are effective modalities for treatment of grades 2–4 keratoconus, but MyoRing had a superior capability in improving the keratoconus parameters as well as in halting the progression of the disease.

Contralateral assessment of sub-Bowman keratomileusis (SBK) microkeratome suction duration on laser-assisted in-situ keratomileusis (LASIK) flap characteristics

PurposeTo describe the effect of prolonging the standard suction duration during laser-assisted in-situ keratomileusis (LASIK) and its effect on flap thickness and hinge length using sub-Bowman keratomileusis (SBK) microkeratome. MethodsFifty-six eyes (28 patients) were included and divided into 2 groups; Group-A: eyes with flatter corneas (36 eyes, 18 patients) and mean keratometric readings ranging from 40.13 to 43.71 diopters (D). Group-B: eyes with steeper corneas (20 eyes, 10 patients) with mean keratometric readings ranging from 43.85 to 46.72 D. One-Use-Plus SBK microkeratome was used for flap creation. For right eyes, flap was created immediately once suction was built up. In left eyes, the surgeon waited for 10 s after suction was built up before flap creation. Flap hinge length and flap thickness were measured using surgical caliper and ultrasonic pachymetry, respectively. ResultsStatistically significant differences were observed in corneal flap hinge size between right eyes versus left eyes, with a mean of 3.98 ± 0.48 vs. 3.78 ± 0.55 mm (p < 0.001). Mean flap thickness in both eyes did not prove to be statistically significantly different with either surgical technique (90.2 ± 1.68 vs. 90.07 ± 1.44 μm, p = 0.8). Sub-group analysis of Group-A vs. Group-B revealed hinge sizes that were significantly larger in steeper corneas (p < 0.01 and p < 0.05, respectively). However, flap thickness in both groups was unaffected by surgical procedure (p = 0.5). ConclusionsIncreasing suction duration increases flap hinge length and stabilizes the flap, especially in steeper corneas.

Impact of Collagen Cross-linking on Psychological Distress and Vision and Health-Related Quality of Life in Patients With Keratoconus.

To evaluate the changes in psychological distress level and quality of life (QoL) scores of keratoconus (KC) patients 1 year after corneal collagen cross-linking (CXL). Observational cross-sectional study. Thirty-three, consecutive progressive KC patients who received CXL treatment were enrolled in the study. All patients were evaluated before and 1 year after CXL ophthalmologically and psychologically. Main outcome measures were the visual, refractive, and topographic changes and the Beck Depression Inventory, State-Trait Anxiety Inventory (STAI), Short Form-36 (SF-36), and The National Eye Institute Visual Function Questionnaire (NEI-VFQ-25). There were significant improvements in the keratometric readings at flat axis, steep axis, the mean keratometric reading, the corneal astigmatism (Kast), and the maximum keratometric reading. State-Trait Anxiety Inventory-II scores, QoL dimensions, such as physical role difficulty, general health, mental health, ocular pain, near activities, distance activities, peripheral vision, and mental health scores, and the composite score of NEI-VFQ-25, were higher after surgery. There was a positive correlation between the changes observed in Kast and mental health; a negative correlation between the changes in Kast and STAI-II, and a negative correlation between the changes in mental health and STAI-II. Change in STAI-II has significantly predicted the improvement observed in general health. Our results suggested lower trait anxiety and better vision-related and health-related QoL in KC patients 1 year after successful CXL treatment. Better QoL in these patients seems to be related not only with the visual and refractive results but also improvement observed in trait anxiety.

Descemet membrane endothelial keratoplasty: early results in endothelial diseases

Purpose The aim of the study was to evaluate the intraoperative complications and clinical outcome of descemet membrane endothelial keratoplasty (DMEK) in eyes with endothelial diseases. Design The study was designed as a prospective noncomparative interventional trial. Patients and methods In 13 eyes with visually significant endothelial diseases, the diseased endothelium and descemet's membrane were stripped and replaced with a donor graft consisting of endothelium and descemet's membrane. Intraoperative and postoperative complications were evaluated. Best spectacle corrected visual acuity, subjective and objective refraction, keratometric readings, endothelial cell density, and central corneal thickness at 3 months were documented. Results Seventeen DMEK procedures were performed. Reinjection of air into the anterior chamber was needed in nine eyes and the procedure failed in five eyes, requiring a repeat DMEK. Three months postoperatively all eyes showed a mean best spectacle corrected visual acuity of 0.36 ± 0.28 log MAR, a mean keratometric reading of 44.7 ± 1.7 D, a mean astigmatism of 2.16 ± 1.04 D, a mean endothelial cell density of 1881.71 ± 213.39 cells/mm 2 , and a mean central corneal thickness of 501 ± 27.52 μm. Conclusion Although many challenges exist when performing DMEK, this technique allows a quick and complete restoration of the visual potential in patients with corneal endothelial disorders.

Comparison of corneal thickness and curvature in myopic and keratoconic eyes of patients from French Caribbean Isles and continental France

To evaluate the corneal thickness and curvature of myopic and patients with keratoconus from two countries. This cross-sectional study was conducted at Cabinet Opale, Fort de France, French West Indies and University Hospital of Bordeaux, France. Corneal thickness and curvature were assessed in 170 keratoconic eyes of 89 residents of the French Caribbean Islands (FCI) and 159 keratoconic eyes of 91 residents of the Aquitaine region of southwest France. A group of age-matched keratoconus-free patients who had been referred for refractive surgery owing to myopia (173 FCI [173 eyes; 87 individuals] and Aquitaine [181 eyes; 93 individuals]) were also assessed. The mean age at keratoconus diagnosis was significantly higher among FCI than Aquitaine residents (p = 0.009). The mean keratometric (Km) reading was statistically higher for keratoconic FCI than Aquitaine patients, at 48.06 versus 46.21 diopters (p = 0.001). This difference was more pronounced among patients aged >40 years than those ≤40 years (p = 0.009). Patients with keratoconus showed no significant difference in mean central corneal thickness and thinnest corneal point values, irrespective of region. Myopic individuals from the FCI, however, had significantly lower mean central corneal thickness and thinnest corneal point measurements than Aquitaine myopics, irrespective of age group (p ≤ 0.0008). The corneas of patients with keratoconus of African-Caribbean and Caucasian origins are of similar thickness. Myopic African-Caribbean patients referred for refractive surgery tend to present with thinner corneas than Caucasians.

Factors Influencing the Changes in Coma-like Aberrations after Myopic Laser in Situ Keratomileusis

Purpose: To assess factors affecting changes in coma-like aberrations after myopic laser in situ keratomileusis (LASIK).Methods: We retrospectively examined 91 eyes of 48 patients undergoing LASIK (mean patient age ± standard deviation, 29.6 ± 8.1 years; gender, 29 male and 19 female; manifest refraction, −4.76 ± 1.42 diopters). We quantitatively assessed the values of coma-like aberrations for 4-mm and 6-mm pupils using a Hartmann-Shack aberrometer before and 3 months after surgery. Multiple regression analysis was used to assess the relevant factors of the changes in coma-like aberrations.Results: The mean changes in coma-like aberrations for 4-mm and 6-mm pupils were 0.08 ± 0.09 μm and 0.31 ± 0.30 μm, respectively. Explanatory variables relevant to the changes in coma-like aberrations were, in order of influence, amount of spherical equivalent correction (partial regression coefficient B = 0.022, p <0.001 for a 4-mm pupil, B = 0.090, p <0.001 for a 6-mm pupil), and surgical technique (B = −0.062, p = 0.01 for a 4-mm pupil, B = −0.169, p = 0.03 for a 6-mm pupil). No significant correlation was seen with other clinical factors such as age, gender, astigmatism correction, mean keratometric readings, central corneal thickness, or eye tracking (with or without).Conclusions: High myopic eyes requiring larger amounts of laser correction and eyes undergoing conventional LASIK tend to induce more coma-like aberration after surgery. Wavefront-guided LASIK may be a better surgical approach for preventing the induction of coma-like aberrations, especially in eyes with high myopia.

‘Expanding bubble’ modification of ‘big-bubble’ technique for performing maximum-depth anterior lamellar keratoplasty

To describe a new technique for performing maximum-depth anterior lamellar keratoplasty. This was a case series study using a novel method. We introduce and describe a new sign (sunny-side up sign) that reveals the presence and extent of the air bubble at the Descemet membrane (DM)-stroma interface. We also report a novel technique to expand the bubble by injecting viscoelastic material into the bubble cavity and to excise the stromal tissues within the trephination area almost completely. The follow-up period ranged from 12 to 16 months. In all patients we recorded the best spectacle-corrected visual acuity, keratometry, and endothelial cell count preoperatively and postoperatively and the air bubble diameter using the sunny-side up sign. In eight of nine patients, a big bubble formed. The size of the air bubble ranged from 2 to 7 mm. All the bubbles were expanded to 8 mm and the bare DM throughout the trephination area was obtained in all cases. The postoperative mean keratometric readings were reduced compared with the preoperative mean keratometric readings. The BSCVA was increased postoperatively compared with the preoperative acuity. The difference between the preoperative and postoperative endothelial cell counts was not statistically significant. The early outcomes in our series using the expanding bubble technique suggest that it is safe and easy in performing maximum-depth anterior lamellar keratoplasty.

Factors affecting corneal hysteresis in normal eyes

To evaluate factors affecting corneal hysteresis (CH) in normal eyes. We examined 86 normal eyes of 43 healthy volunteers (age, 39.1 +/- 14.5 years (mean +/- standard deviation); range, 19 to 68 years; gender, 26 men, 60 women; manifest refraction, -2.25 +/- 2.89 diopters (D); range, -9.13 to 3.88 D). We quantitatively assessed the value of CH using an Ocular Response Analyzertrade mark (Reichert Ophthalmic Instruments). We carried out this measurement three times, and the average value was used for statistical analysis. Multiple regression analysis was used to assess the relevant factors of the CH. The mean CH was 10.2 +/- 1.3 mmHg. Explanatory variables relevant to the CH were, in order of magnitude of influence, the central corneal thickness (CCT) (partial regression coefficient B = 0.022, p < 0.0001), and the intraocular pressure (IOP) (B = -0.119, p = 0.04). No significant correlation was seen with other clinical factors such as age, gender, manifest refraction, or mean keratometric readings. Eyes with thinner CCT and eyes with higher IOP are more predisposed to have lower CH. Refractive surgeons should, from a biomechanical viewpoint, take not only CCT but also IOP into consideration before performing keratorefractive surgery.

Frequency and predicting factors of surgical complications in cataract surgery performed under topical anaesthesia

Frequency and predicting factors of surgical complications in cataract surgery performed under topical anaesthesia