Changes In Astigmatism Research Articles

Changes in Corneal Higher-order Aberrations and Astigmatism after Upper Eyelid Surgery

Purpose: We investigated the effects of upper eyelid surgery on corneal higher-order aberrations and astigmatism.Methods: We enrolled 38 patients (66 eyes) who underwent blepharoplasty and 48 (81 eyes) who underwent levator resection. The marginal reflex distance1 (MRD1), corneal astigmatism, and corneal higher-order aberrations were measured preoperatively, and at 6 months postoperatively, and the two groups were compared.Results: Corneal astigmatism decreased significantly in the ptosis repair group (p < 0.001) but there was no significant change in the axis of astigmatism. Preoperative third-order and coma-like aberrations were significantly more common in the ptosis repair group than in the other group (p = 0.027 and p = 0.044, respectively); both decreased significantly after the operation (p = 0.030 and p = 0.006, respectively). The decrease in MRD1 and changes in the two aberrations showed a significantly stronger negative correlation in the ptosis repair group than in the other group (b = -0.186; p < 0.001 and b = -0.159; p < 0.001, respectively).Conclusions: For patients with both cataract and ptosis, it is best to perform levator resection surgery before cataract surgery, because corneal higher-order aberrations and astigmatism are improved by levator resection. In turn, this reduces postoperative refractive error and improve vision quality.

Effect of small-incision sutureless cataract surgery on the natural course of astigmatism over 10 to 20 years.

To retrospectively assess astigmatic changes over 10 years and 20 years after small-incision cataract surgery. 5 ophthalmic surgical sites in Japan. Retrospective case series. Data were collected from patients who had undergone phacoemulsification and implantation of an intraocular lens through a 2.2 to 2.4 mm incision. Preoperative corneal and postoperative manifest astigmatism were converted to power vector notations: horizontal/vertical (J 0 ) and oblique (J 45 ) astigmatism components. 422 eyes of 422 patients were followed for 10 years, and data preoperatively and at 1 month and at 1 year, 3 years, 5 years, 8 years, and 10 years postoperatively were analyzed. The mean J 0 decreased significantly ( P < .001, repeated measures analysis of variance) with an against-the-rule (ATR) shift of 0.363 ± 0.433 diopter (D) over 10 years, but the mean J 45 did not change significantly ( P = .150). Double-angle plot analyses also showed similar ATR shifts in all astigmatism groups. In the subgroup analysis conducted in 34 patients who were followed for 20 years, J 0 declined significantly ( P < .001) by 0.649 ± 0.576 D, whereas J 45 did not ( P = .516). The postoperative changes in J 0 and J 45 were not significantly different between eyes with preoperative with-the-rule, ATR, or oblique astigmatism. Postoperative astigmatism continued to shift toward ATR during the follow-up period of 20 years after small-incision cataract surgery, which seems to reflect the natural course of corneal astigmatic changes that commonly occur with aging. ATR astigmatic shifts were similar in both pattern and magnitude regardless of the type of preoperative astigmatism.

Vector analysis of astigmatic correction after single-step transepithelial photorefractive keratectomy and femtosecond-assisted laser in-situ keratomileusis for low to moderate myopic astigmatism.

This study aimed to evaluate the outcomes of astigmatic correction by single-step transepithelial photorefractive keratectomy (TransPRK) and femtosecond-assisted laser in-situ keratomileusis (Femto-LASIK) surgeries. A total of 218 subjects received TransPRK or Femto-LASIK surgery for the treatment of myopia and astigmatism (-2.25 to -0.25 D). Refraction errors and uncorrected (UDVA) and corrected distance visual acuity (CDVA) were examined before and at 3 months after surgery. Astigmatism changes were assessed by vector analysis. Preoperative parameters of the TransPRK group were similar to the Femto-LASIK group. UDVA and CDVA at 3 months were similar between both groups. Manifest refraction (MR) spherical equivalent in the TransPRK group (0 ± 0.20 D) was slightly lower compared with the Femto-LASIK group at 3 months (0.11 ± 0.25 D, P = 0.001). MR cylinder was -0.06 ± 0.19 D in the TransPRK group and -0.02 ± 0.15 D in the Femto-LASIK group at 3 months (P = 0.135). The index of success (IS) was 0.15 ± 0.36 in the TransPRK group and 0.06 ± 0.17 in the Femto-LASIK group (P = 0.125). The correction index (CI) was 1.03 ± 0.19 in the TransPRK group and 1.01 ± 0.11 in the Femto-LASIK group (P = 0.815). For low to moderate myopic astigmatism, TransPRK provided a comparable astigmatic treatment effect as Femto-LASIK. Myopic astigmatism was both slightly overcorrected after TransPRK and Femto-LASIK surgeries.

Bi-directional Refractive Compensation for With-the-Rule and Against-the-Rule Astigmatism in Young Adults.

PurposeThe purpose of this study was to investigate the short-term effect of imposing astigmatism on the refractive states of young adults.MethodsNineteen visually healthy low-astigmatic young adults (age = 20.94 ± 0.37 years; spherical-equivalent errors [M] = −1.47 ± 0.23 diopters [D]; cylindrical errors = −0.32 ± 0.05 D) were recruited. They were asked to wear a trial frame with treated and control lenses while watching a video for an hour. In three separate visits, the treated eye was exposed to one of three defocused conditions in random sequence: (1) with-the-rule (WTR) astigmatism = +3.00 DC × 180 degrees; (2) against-the-rule (ATR) astigmatism = +3.00 DC × 90 degrees; and (3) spherical defocus (SPH) = +3.00 DS. The control eye was fully corrected optically. Before and after watching the video, non-cycloplegic autorefraction was performed over the trial lenses. Refractive errors were decomposed into M, J0, and J45 astigmatism. Interocular differences in refractions (treated eye – control eye) were analyzed.ResultsAfter participants watched the video with monocular astigmatic defocus for an hour, the magnitude of the J0 astigmatism was significantly reduced by 0.25 ± 0.10 D in both WTR (from +1.53 ± 0.07 D to +1.28 ± 0.09 D) and 0.39 ± 0.15 D in ATR conditions (from −1.33 ± 0.06 D to −0.94 ± 0.18 D), suggesting an active compensation. In contrast, changes in J0 astigmatism were not significant in the SPH condition. No compensatory changes in J45 astigmatism or M were found under any conditions.ConclusionsWatching a video for an hour with astigmatic defocus induced bidirectional, compensatory changes in astigmatic components, suggesting that refractive components of young adults are moldable to compensate for orientation-specific astigmatic blur over a short period.

Clinical observations of EVO-ICL implantation and changes in corneal astigmatism using a modified technique

BackgroundImplantable collamer lens (ICL) surgery techniques are constantly progressing. The purpose of this study was to investigate the application effect of the modified technique and its impact on the change in corneal astigmatism in EVO-ICL surgery.MethodsThe analysis of retrospective cohort data included 153 eyes of 81 patients with myopia from July 2018 to May 2020. An EVO-ICL was inserted by modified surgical skills, including a single 3.0 mm corneal incision and no ophthalmic viscosurgical device (OVD) before the insertion of the ICL (modified technique group: 41 cases, 80 eyes) and standard procedure (standard technique group: 40 cases, 73 eyes). Early postoperative intraocular pressure (IOP) was monitored at 2 and 24 h. IOP, corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), vault, and anterior chamber depth (ACD) were measured 1, 6, and 12 months following the initial examination. The corneal endothelial cell density (ECD) was monitored at 6 and 12 months after the operation. Surgically induced astigmatism (SIA) in the total, anterior, and posterior corneal surfaces was analysed 1 month after the operation.ResultsNo serious complications were detected. The two groups had no difference in visual outcomes, ICL vaults, or ACD at any time point (P > 0.05). Two hours postoperatively, IOP was significantly lower in the modified technique group (16.22 ± 2.22 vs. 18.37 ± 1.92 mmHg, P < 0.05) than in the standard technique group. IOP decreased gradually after 24 h to preoperative levels. The postoperative IOP remained stable over a 12-month period. The ECD at 6 and 12 months was not significantly different between the groups (P > 0.05). SIA in the total, anterior, and posterior corneal surfaces were assumed to have no clinically meaningful differences between groups at one month after operation (P > 0.05).ConclusionsThe modified technique is efficient and safe, producing comparable visual and structural outcomes without adversely affecting ECD, and reduces fluctuations in IOP at the early postoperative stages. The auxiliary incision in the standard technique does not increase corneal SIA, which is also a factor to consider for inexperienced surgeons.

Changes in Corneal Astigmatism after Closing Clear Corneal Incision by Simple Hydration Undergoing Phacoemulsification at the Department of Ophthalmology JPMC

Purpose: To determine the mean changes of corneal astigmatism after closing clear corneal incision by simple hydration undergoing phacoemulsification in the eye department of a tertiary care hospital. Methodology: This was a Quasi experimental study conducted at the department of Ophthalmology, Jinnah Postgraduate Medical Center, Karachi, from 30th October 2020 to 29th April 2021. Total 100 patients who underwent phacoemulsification surgery for cataract were included. Changes of astigmatism were measured with Auto-refractometer. Fundus examination was done using +90D lens with a slit lamp. Mean changes in corneal astigmatism were calculated. Pre and post operatively change in astigmatism was compared using paired t-test. Stratification was done. P value ≤0.05 was considered as statistically significant. Results: Mean age was 43.47±11.13 years. There were 54% male and 46% female patients. Mean change of corneal astigmatism was 0.23±0.44 diopter. Mean corneal astigmatism, preoperatively, after 1 week and after 1 month were 1.05±0.05 diopter, 0.69±0.34 diopter and 1.28±0.44 diopter respectively. Highly significant mean difference of corneal astigmatism was observed between preoperatively and after 1 week, preoperatively and after 1 month and also observed between 1 week and 1 month. Conclusion: Closing clear corneal incision by simple hydration undergoing phacoemulsification was found an effective technique for treatment of corneal astigmatism. Keywords: Mean Changes, Corneal Astigmatism, Closing Clear Corneal Incision, Simple Hydration, Phacoemulsification

Toric intraocular lens implantation vs femtosecond laser-assisted arcuate keratotomy for correction of moderate astigmatism in cataract surgery.

To compare toric intraocular lens (TIOL) implantation and femtosecond laser-assisted arcuate keratotomy (FSAK) during phacoemulsification surgery in correction of moderate astigmatism. Clinical research study. Prospective randomized comparison study. Patients with age-related cataract and moderate preoperative corneal astigmatism of 1.25 to 3.0 diopters (D) were randomized into a TIOL implantation group and an FSAK group with symmetrical paired corneal arcuate keratotomies. The preoperative evaluation included corrected distance visual acuity (CDVA), corneal topography, autokeratometry, and ocular biometry. Postoperative examinations were performed at 1 month and 3 months and included CDVA and uncorrected distance visual acuity, manifest refraction, autokeratometry, and corneal topography. Vector analysis of astigmatic changes was performed using the Alpins vector method. This study comprised 75 eyes from 67 patients. The mean residual refractive astigmatism at 3 months was -0.63 ± 0.55 D in the TIOL group and -0.90 ± 0.53 D in the FSAK group ( P = .037) and was ≤1.00 D in 32 eyes (84%) and 25 eyes (64%), respectively. There were no statistically significant differences between the 2 groups in difference vector, angle of error, magnitude error, or correction index in the 3-month follow-up. The index of success was 0.32 ± 0.33 D in the TIOL group and 0.48 ± 0.29 D in the FSAK group ( P = .029). TIOL implantation showed better results in correcting moderate astigmatism. Despite this, FSAK is shown to be a safe technique for reducing astigmatism.

Predictors of Femtosecond Laser–Assisted Arcuate Keratotomy Efficacy for Astigmatism Correction in Cataract Surgery

To evaluate the predictors related to the efficacy of epithelium- and Bowman membrane-penetrating femtosecond laser-assisted arcuate keratotomy (FSAK) in the treatment of preoperative astigmatism in patients with cataracts and to clarify the predictive role of the incision-to-limbus distance. This retrospective study included patients who underwent femtosecond laser-assisted cataract surgery combined with FSAK using the LenSX platform (Alcon Laboratories, Inc) at Beijing Aier-Intech Eye Hospital from March 2017 to December 2021. The Lenstar LS900 (Haag-Streit, Inc) was used to measure the horizontal corneal diameter, and ImageJ software (National Institutes of Health) was used to measure the vertical corneal diameter and incision-to-limbus distance. Finally, the measured values were converted. Changes in corneal astigmatism before and 3 months after surgery were analyzed using Alpins vector analysis. Correlation analysis and regression analysis were used to evaluate the factors associated with surgically induced astigmatism (SIA) in preoperative ocular biometric parameters. The study included 94 eyes of 94 patients. The mean target induced astigmatism was 1.36 ± 0.44 diopters (D), SIA was 0.82 ± 0.43 D, and mean difference vector was 0.70 ± 0.40 D. Pearson correlation analysis and univariate regression analysis showed that preoperative corneal astigmatism, arcuate keratotomy arc length, incision-to-limbus distance, and astigmatism type were significant predictors of SIA. Multiple variable regression analysis included parameters such as age, arcuate keratotomy arc length, and incision-to-limbus distance and established a multiple regression model of SIA (all P < .01). The incision-to-limbus distance was a significant independent predictor of SIA, and inclusion of this parameter may further improve the accuracy of the nomogram. [J Refract Surg. 2022;38(8):480-486.].

The Utility of Peripheral Vitrectomy Featuring Scleral Indentation during Scleral Fixation of Intraocular Lenses

Purpose: We evaluated the utility of peripheral vitrectomy featuring scleral indentation; we compared a group who underwent peripheral vitrectomy to a control group for whom vitrectomy was combined with scleral fixation of intraocular lenses (IOLs) in patients exhibiting IOL dislocations.Methods: From January 2018 to December 2020, 20 eyes of patients evidencing IOL dislocations that underwent total vitrectomy, IOL removal, and IOL scleral fixation were evaluated; peripheral vitrectomy with scleral indentation was performed in 10 patients. All operations were performed by the same surgeon. We excluded patients with follow-up periods less than 6 months, those with a history of retinal and/or glaucoma surgery, and patients with retinal abnormalities or glaucoma that might significantly compromise visual acuity. The postoperative best-corrected visual acuity, intraocular pressure, astigmatism changes, and complications were retrieved from the medical records.Results: Six months after surgery, the best corrected visual acuity was 0.95 (the Snellen measure) in the group who underwent peripheral vitrectomy featuring scleral indentation, and 0.60 in the control group (p = 0.029). The total astigmatism values were 0.48 diopter in the former and 2.80 diopter in the latter group; the difference was significant (p &lt; 0.001).Conclusions: In patients with IOL dislocations who underwent vitrectomy combined with IOL scleral fixation, improvements in visual acuity were further enhanced when peripheral vitrectomy was combined with scleral indentation. Complete removal of the peripheral vitreous may stabilize IOL positioning by the remnant vitreous.

Comparison study between Pilocarpine and Tropicamide drops on corneal topography and their effect on IL-6 and TNF-α levels in tear

Corneal stability is essential for contact lenses and refractive surgery. It seems that paralyzing eye drops or expansion of the ciliary muscle affect the radius of curvature and the strength of the cornea, and this effect is to increase the strength of the cornea during muscle spasm and decrease it in the relaxed state of the muscle. On the other hand, different factors (such as contact lens wear, ocular surface disorders, trauma, dry eye, and immunosuppression) could alter the immune defense mechanisms of the outer eye and permit microorganisms to invade the cornea. Therefore, the present study compared Pilocarpine and tropicamide drop on corneal topography and their effect on IL-6 and TNF-α levels in tear. This prospective study was performed on sixty normal and healthy eyes of sixty volunteers with a mean age of 38.19 years and without any ocular pathology. Volunteers were divided into two groups of thirty. In the first group, corneal topography of both eyes was measured before and 30 minutes after instillation of topical tropicamide 1% in only one eye. The other eye was the control eye, and no drop was given. The same routine was performed in the second group, except that subject received one drop of Pilocarpine 2% in one eye. Statistical comparison between groups for the central corneal power, corneal radius, and corneal astigmatism was performed using paired t-test. IL-6 and TNF-α levels in tear were analyzed using two Luminex commercial assays with Bio-Plex 200TM System (Bio-Rad, Hercules, California, USA). In group 1, no significant changes were found in corneal radius, power, and astigmatism. However, in group 2 subjects who received pilocarpine eye drops, the mean corneal radius value decreased significantly by 0.05 mm. The mean corneal power increased by +0.32 D. There was no significant difference change in corneal astigmatism in both groups. Evaluation of IL-6 levels in tears showed a significant difference between the control and treatment groups (P = 0.041). But no significant difference was observed between the Pilocarpine and the Tropicamide groups (P = 0.761). Evaluation of TNF-α level in tears also showed no significant difference between these groups (P = 0.088). Pilocarpine induced ciliary muscle contraction, which may cause pressure on the corneal limbus and scleral spur, resulting in changes in corneal curvature. But tropicamide eye drop did not affect corneal radius and other corneal parameters, and corneal topography can be carried out after the installation of tropicamide eye drop.

Comparison of Long-Term Corneal Astigmatic Changes After Cataract Surgery in Eyes With Superior or Horizontal Clear Corneal Incisions

To compare long-term corneal astigmatic changes after stabilization of surgically induced astigmatism (SIA) subsequent to phacoemulsification between eyes that underwent superior clear corneal incision (CCI) or horizontal CCI. Retrospective, comparative case series. We examined the anterior corneal astigmatism of eyes that underwent a 2.4-mm superior CCI (superior CCI group, n=43) or horizontal CCI (horizontal CCI group, n=43) preoperatively, on the postoperative day that SIA stabilized (baseline), and at ≥7 years post-baseline using an autokeratometer. Corneal astigmatic changes from baseline to ≥7 years post-baseline (mean duration 8.74 years in the superior CCI group and 9.05 years in the horizontal CCI group) were decomposed to vertical/horizontal (Rx) and oblique astigmatic change components (Ry) and were compared between the 2 groups. The mean corneal astigmatism components changed significantly toward against-the-rule (ATR) astigmatism in the superior CCI group and with-the-rule astigmatism in the horizontal CCI group within 6 months postoperatively. After stabilization of the SIA, both groups showed a significant increase in the mean Rx and no significant change in the mean Ry over approximately 9 years, indicating a long-term ATR shift. The mean changes in the Rx and Ry did not differ significantly between the superior and horizontal CCI groups. Double-angle plots revealed a similar degree of ATR shift between the 2 groups over the 9 years. After stabilization of the SIA, a similar degree of ATR change occurred subsequent to superior and horizontal CCIs over approximately 9 years, suggesting that CCI direction does not affect long-term astigmatic changes.

Refractive changes and visual quality in patients with corneal edema after cataract surgery

BackgroundTo assess visual quality and stabilization of refractive changes in corneal edema patients after cataract surgery, using visual acuity (VA) and contrast sensitivity measurements.MethodsSixty-one eyes were analysed, twenty-three with and thirty-eight without corneal edema. Uncorrected and corrected distance VA (UDVA and CDVA) were determined with an EDTRS chart, the contrast sensitivity function (CSF) under photopic and mesopic illumination conditions with a CVS-1000e chart, clinical refraction, and corneal topography. Measurements were taken preoperatively, 1–2 days, 1 and 3-months after surgery. Clinical refraction was converted to vector notation (M, J0, J45) and SPSS v26.0 was used for data analysis.ResultsAn improvement of VA was observed through the postoperative period; changes between visits were significant for CDVA in both groups and for UDVA in the edema sample. Significant astigmatic changes (J0,J45) between visits were not observed, but M values showed a hyperopic tendency in the edema group and a myopic shift in the control group that did not change between visits, with statistically significant differences between groups. Controls had significantly better contrast sensitivity at high spatial frequencies. Under mesopic conditions, global contrast sensitivity losses were observed in the edema group, which improved between visits in the middle frequency range.ConclusionCorneal edema patients had a significant reduction of CDVA, and frequency-selective sensitivity losses that evidence a visual quality loss. Clinical refraction may improve visual quality, but in edema patients these losses are related to corneal changes, which did not change at three months after surgery.

Retropupillary iris claw lens versus Gore-Tex assisted scleral fixated intraocular lens in children with large lens subluxations.

Purpose:To compare the functional outcome of retropupillary iris claw lenses (RPIC-IOL) and scleral fixated intraocular lenses (SFIOL) in children with large lens subluxations.Methods:Sixty eyes of patients between 6 and 18 years of age having >7 clock hour lens subluxation were included and equally divided into group A (RPIC-IOL implantation) and group B (Gore-Tex sutured SFIOL implantation). Cases with anterior and posterior segment abnormalities, trauma and glaucoma were excluded. Primary outcome was improvement in best-corrected visual acuity (BCVA) at 1.5 years. Secondary outcomes were assessment of intraocular lens (IOL) tilt, mean change in astigmatism at 1.5 years, and median operating time. All surgeries were performed by the same surgeon.Results:The mean improvement in BCVA in group A was 0.28 ± 0.41 logMAR and group B was 0.44 ± 0.45 logMAR (P = 0.3). Significant IOL tilt was seen in 4 eyes in group A (13.33%) and 5 eyes in group B (16.66%) (P = 0.120). Mean change in astigmatism was 4.38 ± 5.9D in group A and 4.91 ± 4.4D in group B (P = 0.299). The median operating time was 40 min in group A and 90 min in group B (P < 0.001). No significant posterior segment complications were seen in either technique.Conclusion:Both procedures had comparable visual outcomes. RPIC-IOL implantation was relatively quick and comparatively easier; it may be preferred in cases with high risk of retinal detachment.

Early postoperative astigmatism in 2-mm manual small incision cataract surgery with phacofracture.

Purpose:India’s cataract surgery rate has been hovering around a creditable 6000 per million population but the coverage is variable across the geography and demography with sharp urban rural divide. Smaller incisions in manual small incision cataract surgery (MSICS) with phacofracture have been credited with lower astigmatism and faster recovery, which is especially useful for patients traveling for surgeries.Methods:In this retrospective chart analysis based observational study of 66 eyes, we describe the early postoperative results with 2 mm MSICS with phacofracture.Results:The mean spherical equivalent of the autorefractor measured astigmatic error changed marginally to −0.51 diopters (SD = 0.58) from −0.44 diopters (SD = 0.42) (t = −8.410, P = 0.0) translating to mean change in astigmatism of 0.14 DCyl when the axis was ignored. The keratometric difference between steepest and flattest axis of the anterior surface of the central 3 mm zone of the cornea changed from a mean of 0.89 diopters (SD = 0.55) to 1.39 diopters (SD = 1.03). The visual acuity improved to mean logarithm of the minimum angle of resolution (logMAR) score of 0.27 (SD = 0.33) at 1 week and 0.007 (SD = 0.04) which corresponds to 6/6P on Snellen’s acuity at 1 month or more.Conclusion:A 2 mm MSICS with phacofracture can deliver low astigmatism and good visual recovery in cataract surgery. The study underlines the need for considering the refraction at anterior and posterior corneal interfaces when the triplanar incision with separate interfaces is used.

Changes in Astigmatism and Visual Acuity after Pterygium Excision in the Ashanti Region of Ghana

Background: Pterygium is a conjunctival subepithelial fibrovascular growth commonly occurring in the inter-palpebral conjunctiva nasally or temporally. It tends to grow over the cornea, leading to visual impairment due to various factors, including astigmatism.&#x0D; Methods: This was a prospective, multi-centered, hospital-based, interventional study carried out within 12 months in three eye centers in the Ashanti region of Ghana. One hundred eyes of 100 adults (≥18 years) with primary pterygia were recruited. Operated eyes had measurements of uncorrected visual acuity (UVA), aided visual acuity (AVA), and keratometry readings (K-readings) before pterygium excision with conjunctival autograft (CAG), 2 weeks after surgery, and 6 weeks after surgery.&#x0D; Results: The mean age of patients was 47.1±11.5 years. The mean pre-operative astigmatism was 5.0±5.9 D. The mean astigmatism values at 2 and 6 weeks post-operatively were 1.7±1.5 and 1.3±1.0 D, respectively. Eighty-nine eyes had AVA ≥6/12 (0.11 mean logMAR) before surgery, whereas 97 eyes had AVA ≥6/12 (0.02 mean logMAR) 6 weeks after surgery, and the increase was statistically significant.&#x0D; Conclusion: Pterygia excision with CAG leads to an approximately fourfold reduction in mean pterygium-induced astigmatism by 6 weeks after surgery.

Astigmatic Change in Manual Small Incision Cataract Surgery (MSICS) with Chevron Type of Incision

Astigmatic Change in Manual Small Incision Cataract Surgery (MSICS) with Chevron Type of Incision

Impact of cone base diameter on outcomes of deep anterior lamellar keratoplasty in keratoconus.

To evaluate the outcomes of deep anterior lamellar keratoplasty (DALK) in treatingkeratoconus in relation to cone base diameter (CBD). A retrospective study. Sixty-one eyes of 49 keratoconus patients who underwent DALK between 2009 and 2018 were enrolled. Preoperative and postoperative uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), spherical equivalent, and astigmatism were measured. Scheimpflug tomography (Pentacam) was used to measure the cone base area (CBA) and CBD using MATLAB software. The mean age of the patients was 20.8 ± 6.1years old, and the mean follow-up time was 27.3 ± 15.2months. Mean UCVA improved from 1.23 ± 0.48 to 0.57 ± 0.27 (LogMAR, 95% CI [0.52, 0.80]; P < 0.001), whereas mean BCVA improved from 0.98 ± 0.55 to 0.18 ± 0.13 (95% CI [0.66, 0.94]; P < 0.001). The mean spherical equivalent decreased by 4.53 ± 5.65 D (95% CI [- 6.25, - 2.82]; P < 0.001), with little change in astigmatism (95% CI [- 1.39, 0.64]; P = 0.457). The postoperative BCVA in the patients with CBD < 5.07mm and corneal curvature ≥ 55D was significantly better than those whose CBD ≥ 5.07mm (0.14 ± 0.09 vs 0.25 ± 0.15, P = 0.001). The follow-up time was negatively correlated with the BCVA (P = 0.004). In this study, outcomes of DALK in keratoconus were related to CBD and corneal curvature. Patients with large CBD (≥ 5.07mm) where the corneal curvature ≥ 55D are more likely to have poor visual outcomes after DALK.

Effect of depth of the sclerocorneal incision on postoperative corneal astigmatism in manual small-incision cataract surgery.

Purpose:To determine the effect of depth of scleral tunnel incision measured by anterior segment OCT on postoperative corneal astigmatism by comparing the change of magnitude of corneal astigmatism between superficial and deep sclerocorneal tunnel incision in manual small-incision cataract surgery (SICS).Methods:Depths of sclerocorneal incision of 72 eyes of patients undergoing uncomplicated manual SICS and attending regular follow-up schedule were assessed with anterior segment OCT at 6-week post-op follow-up.Results:The overall mean ± standard deviation (SD) change of astigmatism for superficial incision, that is, ≤399 mm, was 0.44 ± 0.30 and that for deeper, that is, ≥400 mm, was 0.13 ± 0.48 and the change was significantly higher in ≤399 mm group than in ≥400 mm group (P = 0.003). In both superior and temporal incision locations, the mean ± SD change of astigmatism for ≤399 mm incision was 0.48 ± 0.29 and 0.40 ± 0.30, respectively, and that for ≥400 mm was 0.03 ± 0.34 and 0.23 ± 0.57, respectively. The change of astigmatism was significantly higher in ≤399 mm incision group overall (P = 0.003) and also higher in both superior and temporal incision location groups (P = 0.001 and P = 0.479, respectively).Conclusion:The depth of sclerocorneal incision had a statistically significant effect on the change of astigmatism following manual SICS, with superficial incision (≤399 μm) causing a higher change than deeper incision (≥ 400 μm).

Significant increase in astigmatism in children after study at home during the COVID-19 lockdown

ABSTRACTClinical relevanceEvaluating changes in refractive astigmatism after ‘study at home’ during the COVID pandemic may shed light on the aetiology of refractive errors.BackgroundTo investigate whether there has been a change in the proportion of astigmatism among primary school children after the school closure period during the COVID-19 pandemic.MethodsThis observational study compared cross-sectional (2018: n = 112; 2020: n = 173) and longitudinal data (n = 38) collected from two vision screenings, one in 2018 and the other after the school closure period in 2020, in the same primary school for children aged 8–10 years. Non-cycloplegic refraction and axial length were measured using an open‐field auto‐refractometer and IOL Master, respectively. A questionnaire focusing on demographic information, near-work time, and outdoor activities was administered to parents of all participants.ResultsWhile there were no significant differences in age, gender, or monthly family income between the two cohorts, astigmatism proportion (Cyl ≥ 0.75 D) in 2020 was 1.5-fold higher than that in 2018 (49.1% vs. 33.9%). The median cylindrical power was significantly higher in 2020 in older children (9 or 10 years old). More importantly, the children participating in both vision screenings had cylindrical power and J0 astigmatism significantly increased by 0.35 ± 0.40 D and 0.21 ± 0.25 D, respectively.ConclusionA significant increase in astigmatism (both proportion and magnitude) was found after the school closure period. Further studies are needed to investigate the origin of this increased astigmatism.

Factors associated with corneal astigmatism change after ptosis surgery.

To evaluate the predictive factors of postoperative corneal astigmatism change in ptosis patients who underwent ptosis surgical repair. Patients who underwent levator resection at Oculoplastic service of the Department of Ophthalmology, Naresuan University Hospital, Thailand between September 2017 and August 2019 were retrospectively evaluated. Changes in degree and axis of corneal astigmatism after ptosis surgery were compared based on patient factors consisting of age at operation, sex, preoperative margin-reflex distance (MRD) 1, and preoperative degree and axis of corneal astigmatism. Forty-two eyes of 28 patients were included in the study. Wilcoxon signed ranks test showed a significant postoperative corneal astigmatism change only in a subgroup of eyes with preoperative astigmatism of ≥1.5 diopters (D; P=0.006). Furthermore, 72.2% (13/18) of the eyes with preoperative astigmatism of ≥1.5 D showed a reduction of astigmatism after eyelid surgery, with the mean astigmatic change of 0.65 D. Majority of preoperative eyes demonstrated with-the-rule astigmatism pattern (45.2%), of which 57.9% showed a reduced degree of astigmatism. In patients undergoing ptosis surgery, the data demonstrate for the first time the association between postoperative corneal astigmatism change and a preoperative corneal astigmatism of ≥1.5 D. Thus, we encourage considering severity of corneal astigmatism prior to cataract or refractive surgery planning in ptosis patients, especially with toric-intraocular lens, to avoid the possibility of calculation error.