[Significant Increase in Astigmatism after Cycloplegia in Two Children]

Two cases with high corneal astigmatism and mixed astigmatism were reported. Both cases showed significantly increased astigmatism after cycloplegia. Combined with the patients' refractive error, corneal topography and wavefront aberration changes, the possible causes were analyzed. Aberration changes caused by pupil dilation, corneal astigmatism differences in different diameter ranges, and changes in lens astigmatism before and after cycloplegia may lead to increased astigmatism after cycloplegia. It was found that cycloplegic refraction may not accurately reflect the refractive status in daily life for children with high corneal astigmatism, especially mixed astigmatism. Because children need refractive correction in the state of natural pupil, it is recommended that the cycloplegic refraction result could not be directly used as prescription for such children. The final prescription should be based on the topography and the refraction result under natural pupil.

Clinical outcomes after aphakic versus aphakic/pseudophakic intraoperative aberrometry in cataract surgery with toric IOL implantation

PURPOSE

To determine if there was a clinically significant difference in clinical outcomes after toric IOL implantation based on intraoperative aberrometry (IA), where eyes were measured either in the aphakic state only or both the aphakic and pseudophakic states.

METHODS

A prospective, randomized, contralateral eye study was performed at one site in Poughkeepsie, NY, USA. Subjects included patients presenting for uncomplicated bilateral cataract surgery eligible for toric lens implantation with regular corneal astigmatism in both eyes whose toric IOL implantation was based on IA. One eye was measured when aphakic and the other when both aphakic and pseudophakic. The primary outcome measure was the magnitude of residual refractive astigmatism. Secondary measures included the percentage of eyes with 0.50D or less of residual refractive astigmatism, the spherical equivalent refraction and the time for IA measurement.

RESULTS

Mean residual refractive astigmatism was not statistically significantly different between groups (0.32D ± 0.46D IA_1 vs. 0.23D ± 0.35D IA_2, p = 0.25), nor was the percentage of eyes with a residual refractive cylinder of 0.50D or less (94% in both groups, p = 1.0). The average time to measure the pseudophakic eye was 3 min, 46 s. Aphakic IA measurements appeared to produce better spherical equivalent refractive results relative to preoperative calculations.

CONCLUSION

Pseudophakic IA measurements took nearly 4 min per case. Residual refractive astigmatism was not appreciably lower when pseudophakic IA measurements were made after aphakic IA measurements, which suggests aphakic IA measurements alone provide good clinical results with toric IOLs.

Clinical outcomes of Ankoris toric intraocular lens implantation using a computer-assisted marker system

PURPOSE

To report the clinical outcomes of patients who underwent cataract surgery with implantation of Ankoris monofocal toric intraocular lens (IOL) (PhysIOL SA, Liège, Belgium) using the Zeiss Callisto Eye (Carl Zeiss AG, Dublin, CA).

METHODS

We conducted a retrospective case series of patients who underwent routine cataract extraction and implantation of Ankoris toric IOL using the Zeiss Callisto eye between January 2018 and December 2018 by four senior surgeons. Patients' medical records were reviewed, and clinical outcomes including postoperative refraction, visual acuity outcomes, IOL position and deviation from planned axis were collected.

RESULTS

Fifty-six eyes of 56 patients were included, 48% were female, and the mean age was 70 ± 8 years. Patients with pseudoexfoliation syndrome, glaucoma or keratoconus were excluded from the study. Pre-operative mean corneal astigmatism was 2.38 ± 0.78 diopters (D), and mean implanted IOL cylindrical power was 3.06 ± 1.07 D. IOL rotation 30 days postoperatively was within 5° in 82% of eyes and between 6° and 10° in 10.8% of eyes. Mean postoperative refractive astigmatism 30 days postoperatively was 0.22 ± 0.36 D; in 84% of eyes the postoperative refractive astigmatism was ≤ 0.50 D. IOL rotation significantly increased between day 1 to day 7 postoperatively (1.91 ± 3.15° to 3.18 ± 3.3°, P = 0.001). However, no significant rotation had occurred between day 7 and day 30 postoperatively (P = 0.093).

CONCLUSION

Cataract surgery with implantation of Ankoris monofocal toric IOL using the Zeiss Callisto Eye marking system is predictable and effective in reducing refractive astigmatism.

Comparison of Toric Intraocular Lens Alignment Using Image-Guided System and Manual Marking Technique

OBJECTIVES

The aim of this study was to compare the accuracy of an image-guided system (Callisto eye; Carl Zeiss, Oberkochen, Germany) with the manual marking technique in the positioning of a toric intraocular lens (IOL).

METHODS

A total of 80 eyes of 80 patients who underwent cataract surgery with a monofocal, single-piece, hydrophobic, biconvex, toric, aspheric IOL (Acrysof IQ SN6AT, Alcon Laboratories, Inc., Fort Worth, TX, USA) implantation were included. Before surgery, all of the patients underwent a complete eye examination that included evaluation of uncorrected (UCVA) and corrected distance visual acuity (CDVA), spherical equivalent (SE), astigmatic refraction (AR), keratometry, biometry, as well as meridian registration with the IOLMaster 700 (Carl Zeiss, Oberkochen, Germany), slit lamp examination, intraocular pressure measurement, and dilated retinal examination. The diopter of the toric IOL was calculated with an online calculator (Alcon, Fort Worth, TX, USA). At 3 months post surgery, the UCVA, CDVA, SE, and residual astigmatism were recorded, and the pupils of all of the patients were fully dilated to determine the toric IOL marker positions.

RESULTS

Group 1, the Callisto eye system group, comprised 45 eyes, and Group 2, the manual marking technique group, was composed of 35 eyes. The preoperative values of both groups were statistically similar in terms of the SE, corneal cylinder, axial length, logMAR UDVA, and logMAR CDVA. At postoperative 3 months, there were no significant differences between the 2 groups in the logMAR UDVA, logMAR CDVA, degree of misalignment of toric IOL, or mean deviation from target-induced astigmatism values. The mean deviation degree from the intended axis was 2.04±1.84 in the Callisto eye system group (Group 1) and 3.24±2.64 in the manual marking technique group (Group 2). However, this difference did not have any effect on the logMAR UDVA.

CONCLUSION

The image-guided markerless system was found to be as effective as manual marking in the positioning of toric IOLs.

Mutual comparative analysis: a new topography-guided custom ablation protocol referencing subjective refraction to modify corneal topographic data

Background

Several planning algorithms have been developed for topography-guided custom ablation treatment (T-CAT), but each has its own deficiencies. The purpose of this study is to demonstrate the potential of a novel mutual comparative analysis (MCA) informed by manifest refraction and corneal topographic data and the patient’s subjective perception in correcting ametropia.

Methods

This retrospective review included patients with significant preoperative differences in the power or axis of astigmatism according to the manifest refraction and corneal topographic data (power > 0.75 D and/or axis > 10°). T-CAT planning was designed using MCA. Follow-ups were conducted for at least 6 months.

Results

Seventy-nine patients (121 eyes) were included. The mean preoperative deviation in the astigmatic power and axis were 0.72 ± 0.43 D and 20.18 ± 23.68°, respectively. The average oculus residual astigmatism (ORA) was 0.81 ± 0.32 D (range: 0.08–1.66 D). Six months postoperatively, the mean spherical equivalent refraction was 0.04 ± 0.42 D, and the mean cylinder was − 0.27 ± 0.24 D. The mean efficacy and safety indices were 1.10 and 1.15, respectively. The uncorrected distance visual acuity in 92% of the eyes was the same or better than the corrected distance visual acuity. The angle of error was ±5° in 61% of eyes and ± 15° in 84% of eyes. Residual astigmatism was ≤0.5 D in 91% of eyes. Optical quality and photopic contrast sensitivity did not change significantly (p > 0.05), and the scotopic contrast sensitivity decreased at 3, 6, and 12 cpd (p < 0.05). The vertical coma and horizontal coma of the anterior corneal surface significantly decreased postoperatively but increased during follow-up.

Conclusions

The MCA demonstrated safety, efficacy, accuracy, predictability, and stability and can be used as a complementary and feasible method for T-CAT.

Rotational slit-beam marking: an advanced manual corneal astigmatic marking method for toric intraocular lens implantation

PURPOSE

To evaluate the accuracy of an advanced manual corneal astigmatic marking method for toric intraocular lens (IOL) implantation.

METHODS

From 52 patients, 52 eyes with cataracts and corneal astigmatism were included. The target axis of the toric IOL was marked with the new manual marking method preoperatively and with the Zeiss CALLISTO Eye image-guided system intraoperatively. For the manual method, a slit-lamp with a minimum rotation angle of 5 degrees was used and rotated to the meridian of the toric IOL and incision axes. The relative rotational and vertical deviation of the IOL and incision axes were measured using the digital marker as a reference.

RESULTS

There was no significant difference between the manually marked IOL axis (100.9° ± 65.62°) and the digital mark (100.8° ± 65.76°; P = 0.771). The absolute values of the relative rotational and vertical deviations of the manually marked IOL axis were small, at 2.03° ± 1.44° and 0.46 ± 0.43 mm, respectively. There was no significant difference between the manually marked corneal incision and the digital meridian (P = 0.179). Then, patients were classified into three groups based on the type of astigmatism they had. There was no significant difference in mean absolute deviation among the groups (P = 0.112). The manual incision mark had a relative rotational deviation of 1.65° ± 1.44°. The vertical misalignment of the manually marked incision axis was 0.27 ± 0.30 mm.

CONCLUSION

Rotational slit-beam marking could be an effective and convenient marking method for toric IOL implantation. This method could be a potential alternative in underdeveloped areas where digital image-guided systems are not available.

Clinical application of bicylindric intraocular lens power calculation method

Purpose:

To analyze the reliability of the refractive results prediction obtained in intraocular lens (IOL) calculation using bicylindric power calculation method, with the use of steep and flat keratometry readings compared with the classical mean keratometry calculation method.

Methods:

Fifty-seven eyes of 57 subjects who underwent cataract surgery were included in this prospective study. Optical biometry was performed with IOLMaster 700 and IOL power calculation was performed using both keratometry readings and the surgically induced astigmatism. Four weeks after surgery, subjective refraction was done. Finally, results obtained with both IOL calculation methods were compared.

Results:

Mean spherical equivalent using bicylindric IOL power calculation method was - 0.082 ± 0.296D, and achieved mean spherical equivalent using classical IOL power method with Haigis formula was - 0.088 ± 0.405D. Achieved mean spherical equivalent obtained in subjective refraction after surgery was - 0.101 ± 0.265D. Linear correlation between bicylindric method spherical equivalent calculation and achieved spherical equivalent was statistically significant (r = 0.761, P < 0.001), also correlation between Haigis spherical equivalent calculation and achieved spherical equivalent was statistically significant (r = 0.339, P = 0.010). Emmetropia was achieved in 49 of 57 (85.86%) subjects and bicylindric method calculated that 49 of 57 (85.86%) of subjects would get emmetropia (P = 1.000). Classical IOL power calculation estimated that 38/57 subjects would get emmetropia (66.67%) (P = 0.026).

Conclusion:

The IOL power calculation including both keratometry readings and surgically induced astigmatism seems to be more accurate and provides more precision in refractive prediction than classical calculation method.

Early-stage clinical outcomes and rotational stability of TECNIS toric intraocular lens implantation in cataract cases with long axial length

Background

A major focus of toric intraocular lens (IOL) implantation is the rotational stability, especially in the patients with long axial length (AL). In this study, we aimed to evaluate the clinical outcomes after implantation of TECNIS toric IOL in eyes with long AL and identify factors influencing their early-stage stability with preoperative corneal astigmatism.

Methods

The study population consisted of 64 eyes from 52 cataract patients, and these patients had preoperative corneal astigmatism between 1.0 and 3.7 diopters (D) and underwent phacoemulsification and TECNIS toric IOL implantation. Ophthalmic biological measurements were carried out preoperatively, including AL, anterior chamber depth (ACD), lens thickness (LT), vitreous length (VL), anterior chamber volume (ACV), sulcus-to-sulcus (STS) and keratometric value (K). Clinical examinations, including visual acuity, manifest refraction, keratometry, digital anterior segment photographs with pupillary dilation, were performed at 1 and 3 months after surgery.

Results

The mean best corrected distance visual acuity (BCDVA) was improved from 0.93 ± 0.35 logarithms of the minimal angle of resolution (logMAR) preoperatively to 0.07 ± 0.10 logMAR postoperatively at 3 months after surgery. The mean residual astigmatism (RAS) was 0.91 ± 0.74D at 3 months, which was significantly decreased compared with the preoperative corneal astigmatism of 1.71 ± 0.55 D. The mean absolute rotation of TECNIS toric IOL at 1 and 3 months was 7.42 ± 11.32 degree (°) (0–79°) and 7.48 ± 11.19°(0–79°), respectively. The mean area of capsulorhexis and the overlapped area between capsulorhexis and IOL optic intraoperatively was 21.04 ± 3.30 mm² and 7.40 ± 2.87 mm².A positive correlation was found between IOL rotation and the area of capsulorhexis (p = 0.017) at 3 months after surgery. No correlation was found between IOL rotation and AL (p = 0.876), ACD (p = 0.387), LT (p = 0.523), VL (p = 0.546), ACV (p = 0.480), STS (p = 0.884), K1 (p = 0.429), K2 (p = 0.644), average of K1 and K2 (p = 0.520), intraoperative IOL axial direction (p = 0.396), preoperative corneal astigmatism (p = 0.269) or the overlapped area between capsulorhexis and IOL optic intraoperatively (p = 0.131) .

Conclusions

The large CCC was a risk factor for toric IOL rotation. An appropriately smaller sized CCC was conducive to increase the rotational stability of TECNIS toric IOL implantation in cataract cases with long AL.

An analysis of factors associated with graft topographic outcomes after deep anterior lamellar keratoplasty

PURPOSE

To investigate the correlations between preoperative, operative, and postoperative factors and corneal graft topographic parameters after deep anterior lamellar keratoplasty (DALK) performed in keratoconus-affected eyes.

METHODS

This prospective, interventional study enrolled 44 eyes. Graft topographic parameters, including keratometric astigmatism and the surface regularity index (SRI), were assessed after complete suture removal. Univariate analyses were used to evaluate the effects of preoperative factors (donor quality, donor and recipient age, keratoconus severity), operative factors (graft size, donor button roundness, roundness and centration of the donor-recipient junction), and postoperative factors (time point of suture removal) on postoperative topographic parameters.

RESULTS

The roundness of the donor-recipient junction after complete suture removal had a significant association with the roundness of the donor button after trephination (P = 0.04) and the amount of graft decentration relative to the limbus (P = 0.03). A significant correlation was found between the value of graft decentration relative to the limbus and postoperative keratometric astigmatism (P = 0.001) and between the roundness of the donor-recipient junction and the postoperative SRI (P = 0.02). The flat axis of the keratometric astigmatism and the longer axis of the graft lay in the direction of graft displacement. Other investigated factors had no significant association with postoperative topographic indices.

CONCLUSION

Graft displacement relative to the limbus and roundness of the donor-recipient junction were the main predictors of graft astigmatism and regularity, respectively, after DALK. Noncircularity of the donor button after trephination could increase the graft surface irregularity indirectly by influencing the roundness of the surgical wound.

[Characteristics and analysis of corneal astigmatism in age-related cataract patients over 50 years old]

Objective: To investigate the relationship between corneal astigmatism and age, axial length (AL) in age-related cataract patients over 50 years old. Methods: In this retrospective study, 1 906 eyes of 953 patients with age-related cataract were diagnosed from February 2016 to August 2016 atPeking University People's Hospital, and their demographics, preoperative AL, magnitude and meridian of the corneal astigmatism measured by IOL Master were collected. Restricted cubic splines and Spearman rank correlation coefficients were used to investigate the relationship of the magnitude of cornea astigmatism to age. Chi-square test was used to assess the relationship of the meridian of astigmatism to age, AL and the magnitude of cornea astigmatism. Results: The patients were 410 men and 543 women. The corneal astigmatism was with-the-rule (WTR) in 570 eyes (29.91%), against-the-rule (ATR) in 1 005 eyes (52.73%) and oblique in 331 eyes (17.37%). The mean age was (72±9) years old. The medians (min, max) of AL and corneal astigmatism magnitude were 23.49 mm (19.83 mm to 33.89 mm) and 0.97 D (0.06 D to 4.65 D) in right eyes and 23.41 mm (17.54 mm to 32.09 mm) and 0.92 D (0.11 D to 4.88 D) in left eyes, respectively. The corneal astigmatism was ≥0.75 D in 64.95% (619/953) of the right eyes and 61.59% (587/953) of the left eyes. Among the elderly patients over 65 years old, when the AL was between 22.00-25.99 mm (r=0.186-0.279), the value of corneal astigmatism was positively correlated with age (all P<0.01) in both eyes. The value of ATR corneal astigmatism was positively correlated with age (right eyes, r=0.278, P<0.01; left eyes, r=0.225, P<0.01), while the value of WTR corneal astigmatism had no statistically significant correlation with age (right eyes, P=0.335; left eyes, P=0.633). The prevalence of WTR astigmatism decreased with age from 43.81% (46/105) to 20.73% (51/246) in right eyes and from 40.00% (42/105) to 24.80% (61/246) in left eyes, while the prevalence of ATR astigmatism increased with age from 38.10% (40/105) to 61.38% (151/246) in right eyes and from 33.33% (35/105) to 58.94% (145/246) in left eyes. The prevalence of oblique astigmatism was not significantly changed with age (right eyes, χ(2)=31.986, P<0.01; left eyes, χ(2)=27.686, P<0.01). There was no statistically significant difference in the distribution of corneal astigmatism meridians between different AL groups (right eyes, P=0.497; left eyes, P=0.897). With the increase of the magnitude of corneal astigmatism, the prevalence of oblique astigmatism significantly decreased from 25.45% (85/334) to 0 in right eyes and from 29.78% (109/366) to 1.35% (1/74) in left eyes, while the prevalence of ATR astigmatism significantly increased from 39.82% (133/334) to 79.27% (65/82) in right eyes and from 41.80% (153/366) to 59.46% (44/74) in left eyes (right eyes, χ(2)=72.229, P<0.01; left eyes, χ(2)=72.166, P<0.01). Conclusions: A majority of age-related cataract patients over 50 years old have astigmatism ≥0.75 D before cataract surgery. When the AL is between 22.00 mm and 25.99 mm, the magnitude of corneal astigmatism increases with age among people over 65 years old, especially the magnitude of ATR corneal astigmatism, while the magnitude of WTR corneal astigmatism has no obvious increase with age. The percentage of ATR astigmatism increases while the percentage of WTR astigmatism decreases with age. (Chin J Ophthalmol, 2020, 56: 349-355).

Comparative effects of various types of toric intraocular lenses on astigmatism correction

BACKGROUND

Currently, various types of toric intraocular lenses (IOL) have been manufactured and can be divided into three types according to the location of correction component; front-toric IOL (correction on anterior IOL surface), back-toric IOL (correction on posterior IOL surface), and bi-toric IOL (correction on both anterior and posterior IOL surfaces). In this study, we aimed to investigate the effectiveness of reducing corneal astigmatism of either normal or post-penetrating keratoplasty (PKP) corneas according to the type of implanted toric IOLs.

METHODS

Medical records were retrospectively reviewed in 370 patients who had undergone phacoemulsification with posterior chamber toric IOL insertion (front-toric IOL, back-toric IOL or bi-toric IOL). Subjects were divided into 2 groups; subjects who had no history of corneal disease with corneal astigmatism more than 1.00 diopters (D) (G1) and subjects who received previous PKP with all corneal sutures removed and had corneal astigmatism more than 1.25 D (G2). Preoperatively intended target from SRK/T was evaluated. Refractive astigmatism and its vector analysis (J0, J45), mean numerical error (MNE) and mean absolute error (MAE) were assessed at least a month after cataract surgery.

RESULTS

Mean preoperative corneal astigmatisms were 2.2 D and 4.0 D in G1 and G2, respectively. There was significant reduction of mean postoperative refractive astigmatism to 0.89 D in G1 and to 2.33 D in G2. In G1, bi-toric IOL showed significantly more improved refractive astigmatism than back-toric IOL. In G2, no difference in refractive astigmatism according to toric IOL type was observed. While G2 showed no difference in MNE among toric IOLs, in G1, bi-toric IOL showed significant hyperopic shift compared to back-toric IOL. In both groups, there was no significant difference in MAE according to type of IOL. No postoperative complications were observed.

CONCLUSION

Our study suggests that all types of toric IOL are beneficial in correcting astigmatism of normal and post-PKP corneas. Noticeably, bi-toric IOL showed significantly better results in refractive astigmatism than back-toric IOL in normal cornea. However, bi-toric IOL showed a more hyperopic shift compared to back-toric IOL. Among post-PKP corneas, all types of toric IOL showed similar results.

Wavefront-guided photorefractive keratectomy with and without iris registration: comparison of astigmatic correction

This study aimed to compare the visual outcomes after photorefractive keratectomy (PRK), with and without the iris registration (IR) technology. The retrospective cohort study was performed for wavefront-guided PRK using the Technolas 217z100 excimer laser system in patients with myopic astigmatism (cylinder error - 2 to - 4 diopter [D]). Eyes were divided into IR group (IRPRK) and non-IR group (non-IRPRK). Visual acuity (VA), cylindrical refraction, and the astigmatic vector components using the Alpins method were compared between the two groups preoperatively and 6 months postoperatively. Fifty IRPRK patients (66% female, mean age 30.56 ± 6.31 years) and 50 non-IRPRK (60% female, mean age 29.60 ± 5.63 years) were enrolled. The mean logMAR uncorrected VA improved from 0.89 ± 0.44 to 0.032 ± 0.05 in the IRPRK group (P < 0.001) and from 0.89 ± 0.46 to 0.042 ± 0.06 postoperatively while follow-up in the non-IRPRK group (P < 0.001). No statistically significant differences were observed between the two groups regarding mean uncorrected distance VA (P = 0.4), corrected distance VA (P = 0.5), spherical equivalent (P = 0.16), defocus equivalent (P = 0.18), and absolute cylinder (P = 0.94). More than 90% eyes were within ± 1.00 D of emmetropia in both groups. Moreover, Alpins vector analysis revealed that no significant differences were found in any astigmatic parameters between the two groups (P > 0.05). Wavefront-guided PRK independent of the IR status is effective, safe, and predictable in patients with myopic astigmatism. No statistical significance was observed supporting data for the better outcome of visual acuity and astigmatism correction using IR in comparison with a non-IR system.

Retinal control of lens-induced astigmatism in chicks

PURPOSE

Astigmatism is a refractive error due to meridional differences in refractive powers of lens or cornea. The resulting failure to focus image points in a single plane causes blurred vision at all distances. In this study, using an animal model of lens-induced astigmatism, we tested the hypothesis that induced astigmatism is due to processing of astigmatic retinal image information by the brain, which causes distorted growth in the anterior segment via centrifugal neural projections.

METHODS

To induce astigmatism, +4.00DS/-8.00DC crossed-cylinder-lens goggles were affixed over the right eyes of 7-day-old chicks (P7), with the -8.00DC axis oriented vertically (at 90°) or horizontally (180°) (n = 12 each); the left eyes were without goggles (non-goggled). For all experiments, refractive errors of both eyes were measured by streak retinoscopy, before and after 1 week of lens wear. To test whether neuronal pathways between retina and brain are required, axonal conduction within the eye was blocked by intravitreal injections of tetrodotoxin (TTX; 7 μL of 10^-4M) in phosphate-buffered saline (PBS), or of PBS alone (7 μL); fellow open eyes received PBS alone. Pupillary light reflex (PLR) and optokinetic response (OKR) were measured, to assess the efficacy and duration of TTX action. To test whether retinal circuitry is required, groups of chicks (n = 12 each) were treated at P7 by intravitreal injection of 20 μL of mixed excitotoxins (2 μmol N-methyl-D-aspartate, 0.2 μmol quisqualic acid, 0.2 μmol kainic acid; in water) into goggled or non-goggled eyes, to compromise retinal circuitry needed for emmetropization.

RESULTS

Crossed-cylinder goggles reliably induced refractive astigmatism. Maximum astigmatic error was induced when the cylindrical axis was oriented at 90° (vertically). TTX effectively blocked nerve conduction within the eye for 48 h after injection. Goggled eyes developed astigmatism after treatment with TTX or PBS, but not after excitotoxins.

CONCLUSION

Our hypothesis was rejected. In this model, the compensatory astigmatism induced by crossed-cylinder lenses is intrinsic to the eye, and mediated by visual processing in the retina.

Systematic review and meta-analysis of femtosecond laser-enabled keratoplasty versus conventional penetrating keratoplasty

PURPOSE

The aim of this meta-analysis is to compare femtosecond laser-enabled keratoplasty with conventional penetrating keratoplasty regarding postoperative astigmatism, visual functions, graft rejection, graft failure, and complications.

METHODS

Eligible studies were retrieved from five mainstream electronic databases, including PubMed, Embase, Ovid MEDLINE, Cochrane Library, and ClinicalTrial.gov. Postoperative topographic astigmatism was set as the primary outcome, and best-corrected visual acuity, spherical equivalent, endothelial cell density, graft rejection, graft failure, and complications were chosen as the secondary outcomes. Standard mean difference and risk ratio were the size effects for continuous data and binomial data, respectively. The data were pooled through either the random-effects model or the fixed-effects model based on data heterogeneity. Moreover, subgroup analyses were conducted when the heterogeneity occurred distinctly (I² > 50%).

RESULTS

A total of seven comparative studies were included. The pooled standard mean difference (-0.32, 95% confidence interval: -0.74 to 0.10) showed that femtosecond laser-enabled keratoplasty was not superior over conventional penetrating keratoplasty to decrease postoperative topographic astigmatism (p = 0.14). However, best-corrected visual acuity after femtosecond laser-enabled keratoplasty was significantly better than that after conventional penetrating keratoplasty (p = 0.00, standard mean difference: -0.23, 95% confidence interval: -0.37 to -0.10). Furthermore, endothelial cell density after femtosecond laser-enabled keratoplasty was preserved significantly better (p = 0.03, standard mean difference: 0.63, 95% confidence interval: 0.07-1.20). Moreover, spherical equivalent, graft rejection, graft failure, and complications represented no distinct differences between femtosecond laser-enabled keratoplasty and conventional penetrating keratoplasty (p > 0.05).

CONCLUSION

Femtosecond laser-enabled keratoplasty may not be superior over conventional penetrating keratoplasty in decreasing postoperative topographic astigmatism, but might have advantages to achieve best-corrected visual acuity and endothelial cell density preservation. In addition, the two techniques seem to be comparable regarding spherical equivalent, graft rejection/failure, and complications.

Prevalence of Refractive Errors in Iranian University Students in Kazerun

Purpose:

To determine the prevalence of refractive errors and visual impairment and the correlation between personal characteristics, including age, sex, weight, and height, with different types of refractive errors in a population of university students in the south of Iran.

Methods:

In this cross-sectional study, a number of university majors were selected as clusters using multi-stage sampling in all universities located in Kazerun (27 clusters of 133 clusters). Then, proportional to size, a number of students in each major were randomly selected to participate in the study. Uncorrected and corrected visual acuity, non-cycloplegic objective refraction and subjective refraction were measured in all participants.

Results:

The prevalence and 95% confidence interval (CI) of presenting visual impairment and blindness was 2.19% (1.48–3.23) and 0.27% (0.12–0.62), respectively. Refractive errors comprised 75% of the causes of visual impairment. The prevalence (95% CI) of myopia [spherical equivalent (SE) ≤ –0.5 D], hyperopia (SE ≥ 0.5 D), and astigmatism (cylinder power < –0.5 D) was 42.71% (39.71–45.77), 3.75% (2.85–4.51), and 29.46% (27.50–31.50), respectively. Totally, 49.03% (46.39–51.68) of the participants had at least one type of refractive error. There was a positive association between weight and myopia (1.01; 95% CI: 1.01–1.02), anisometropia (1.03; 95% CI: 1.01–1.06), and refractive errors (1.01; 95% CI: 1.01–1.02). In comparison with the age group 18–19 years, the odds ratio (OR) of astigmatism in the age group 26–27 years was 1.64 (95% CI: 1.03–2.61), and the OR of anisometropia in the age group ≥ 30 years was 0.21 (95% CI: 0.04–0.98).

Conclusions:

The prevalence of refractive errors, especially myopia, is higher in university students than the general population. Since refractive errors constitute a major part of visual impairment, university students should receive special services for providing corrective lenses and glasses to reduce the burden of these disorders.

Effect of corneal marking features on toric intraocular lens alignment

PURPOSE

The purpose of this study was to investigate the relation of the corneal ink mark size, shape, and location with the corneal perimeter in terms of the corresponding corneal axis.

MATERIAL AND METHODS

This study was designed both prospective experimental and literature search. Contact lenses were used to demonstrate the spreading effect of the surgical ink mark. Open-access published corneal images with corneal ink marks were reviewed. Mark size and perimeter of both contact lenses and corneal images were performed in Image J software.

RESULTS

Twenty contact lenses and 15 corneal images with 32 corneal marks, which were obtained from the literature, were included in the study. Mean degree corresponding to the ink size for the group 1 was 8.3° ± 1.2° (range 5.5-10.3), for group 2 was 11° ± 1.1° (range 8-12), for group 3 was 4.2° ± 0.7° (range 3.2-5.5), for group 4 was 4.2° ± 0.7° (range 3.2-5.5), and for group 5 was 6.3° ± 2.5° (range 2-11.5).

DISCUSSION

Theoretically, it is wise to target further located ink mark from central cornea based on the 360/2π × (r2 - r1)/(r1 × r2) × M formula. It has been experimentally shown that the smaller corneal perimeter and closer mark to the central cornea may lead the more significant deviation from the targeted axis. Preoperative manual corneal marking may be more responsible for residual astigmatism than it is thought.

Toric intraocular lens implantation in cataract patients with corneal opacity

Background

To evaluate the effect of toric intraocular lens implantation in cataract patient with corneal opacity and high astigmatism.

Methods

Thirty-one eyes of 31 patients who underwent cataract surgery with toric intraocular lens implantation were included. All patients had corneal opacity with astigmatism. Preoperative total corneal astigmatism was determined considering posterior astigmatism using a rotating Scheimpflug camera (Pentacam®: Oculus, Wetzlar, Germany). At 2 months after toric intraocular lens implantation, we evaluated residual astigmatism, uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA).

Results

Postoperative UCVA and BCVA (0.30 ± 0.17, 0.22 ± 0.16LogMAR) were statistically improved compared to preoperative UCVA and BCVA (1.2 ± 0.34, 1.1 ± 0.30LogMAR, respectively) (P < 0.01). Postoperative residual refractive astigmatism (1.2 ± 0.35D) was statistically reduced compared to preoperative refractive astigmatism (2.4 ± 0.65D) (P < 0.05). Preoperative and postoperative total corneal astigmatism values were not statistically different. All eyes achieved postoperative visual acuity as good as or better than preoperative one. The size of corneal opacity covering pupil had significant negative correlation with postoperative UCVA and BCVA (logMAR) (R = 0.91 P < 0.05 and R = 0.92 P < 0.05, respectively).

Conclusion

Toric intraocular lens implantation can improve UCVA, BCVA, and refractive astigmatism in cataract patient with corneal opacity. The size of corneal opacity covering pupil is the major prognostic factor for postoperative visual improvement. Therefore, toric intraocular lens implantation should be considered for cataract patients who have corneal opacity with high astigmatism.

The prevalence of refractive errors in the Middle East: a systematic review and meta-analysis

PURPOSE

The purpose of the present study was to evaluate the prevalence of refractive errors in the Middle East region.

METHODS

In this meta-analysis, a structured strategy was applied to search databases PubMed, Web of Science, Scopus, and Google Scholar, databases as well as the reference lists of the selected articles to identify cross-sectional studies assessing the prevalence of refractive errors in the Middle East region until September 2019. The outcome measure was the prevalence of refractive errors, including myopia, hyperopia, and astigmatism, in two age groups of ≤ 15 years and > 15 years. The study results were combined using a random effects model at a confidence level of 95%.

RESULTS

The prevalence of myopia, hyperopia, and astigmatism was 4% (95% CI 4, 5), 8% (95% CI 6, 10), and 15% (95% CI 10, 19) in people less than or equal to 15 years and 30% (95% CI 25, 34), 21% (95% CI 15, 28), and 24% (95% CI 16, 31) in subjects over 15 years, respectively. The prevalence of myopia, hyperopia, and astigmatism was 3.5%, 12.4%, and 9.0% in male and 4.2%, 13.1%, and 9.9% in female subjects aged ≤ 15 years, respectively. In subjects aged > 15 years, the prevalence was 31.7%, 14.5%, and 31.5% in males and 31.9%, 11.2%, and 31% in females, respectively.

CONCLUSION

The prevalence of hyperopia is relatively high in Middle Eastern children, while the prevalence of myopia is higher in adults in this region. It seems that astigmatism is not a serious refractive problem in this region compared to the rest of the world.

Scleral fixated intraocular lens by a modified technique: Methods and results

PURPOSE

A certain number of conditions can result in compromised anterior and/or posterior capsular integrity. Several surgical options have been employed for repositioning dislocated intraocular lenses in the absence of adequate capsular support. The purpose of this study is to assess the functional outcomes and complication profile of a modified surgical technique for replacing dislocated intraocular lenses.

MATERIAL AND METHODS

All patients who had undergone the modified surgical procedure for dislocated intraocular lenses between 2012 and 2017 were retrospectively reviewed for visual outcomes and complications. Patient demographic characteristics, pre- and postoperative visual acuity, surgical indications, refractive outcomes, intraocular pressure and postoperative complications were recorded and analysed at baseline and at six months, which was the conclusion of the study. We also present our modified surgical technique.

RESULTS

Sixty-eight eyes of sixty-eight patients (74% male) were included. Mean age at surgery was 58 years (range 4-89 years). Mean best-corrected visual acuity increased significantly from 0.80 (SD±0.2) LogMar to 0.40 (SD±0.1) LogMar (P<0.005). Median astigmatic error at the conclusion of follow-up remained stable. There were no intraoperative complications and a low postoperative complication rate (10.2%), mainly related to the surgical context.

CONCLUSION

Sutureless intrascleral fixation of dislocated intraocular lenses is an option in case of deficient capsular support. Visual outcomes and complication rates are comparable to other case series.

Corneal topography, anterior segment and high-order aberration assessments in children with ≥ 2 diopter astigmatism

PURPOSE

To assess topographic findings, anterior segment parameters and high-order aberrations (HOAs) by using corneal tomography in children with 2 diopters (dp) or more astigmatism.

METHODS

Children with 2 dp or more astigmatism (study group) and children with astigmatism less than 1 dp (control group) were recruited. Corneal astigmatism, mean, steep, flat keratometry (K) findings, anterior and posterior K results and anterior segment parameters including anterior chamber depth, kappa distance, horizontal corneal diameter, mean, central, middle, peripheral corneal thicknesses (CT), white-to-white (WTW) distance and pupil diameter were measured by Galilei G4 Dual Scheimpflug corneal tomography. HOAs were also assessed and compared between groups.

RESULTS

Fifty-eight eyes of 37 children in the study group and 37 eyes of 37 children in the control group were enrolled. The mean ages of groups were 9.7 ± 2.4 years and 9.3 ± 1.6 years in study and control groups, respectively. The mean astigmatism was 3.3 ± 1.1 dp and 0.5 ± 0.3 dp in study and control groups, respectively (p < 0.05). Total corneal astigmatism was 3.3 ± 0.84 dp and 1.14 ± 0.47 dp in study and control groups, respectively (p < 0.05). There was a significant difference between groups in terms of posterior steep K and posterior astigmatism values. Among anterior segment parameters, mean CT and WTW values were statistically different between groups. HOAs were found to be statistically different between groups.

CONCLUSION

Higher posterior corneal astigmatism, thinner mean CT and lower WTW distance were found in children with 2 dp or more astigmatism. Besides, HOAs were much more in these astigmatic children.

Results of Callisto Eye System in Toric Intraocular Lens Alignment

OBJECTIVES

This study was an evaluation of the effectiveness of the Callisto eye image-guided, markerless system (Carl Zeiss Meditec AG, Jena, Germany) in toric intraocular lens (IOL) positioning.

METHODS

The results of a novel, markerless, alignment system used for IOL positioning were analyzed in this retrospective study. Preoperatively, reference image registration was performed with the IOLMaster 700 biometer (Carl Zeiss Meditec AG, Jena, Germany) and transferred to the Callisto eye system, which was used in conjunction with an Opmi Lumera 700 microscope (Carl Zeiss Meditec AG, Jena, Germany). Using the Callisto Z Align technology, a toric IOL was aligned precisely with the steep axis. One day after surgery, the pupil was fully dilated and a thin slit was placed on the marker of the toric IOL and the angle was measured using an axis calculator smartphone application. The degree of the measured angle and the preoperatively determined angle were compared.

RESULTS

Sixty eyes of 46 patients were included. The difference in the absolute angle between the intended and the postoperative (at day 1) axes was a mean of 2.71±1.64°.

CONCLUSION

The Callisto eye image-guided, markerless system successfully provided assistance in precisely positioning the toric IOL.

[Comparison of keratometric measurements obtained by the Verion image guided system with the IOLMaster and the Pentacam before cataract extraction surgery]

Objective: To compare the keratometric measurements of the Verion image guided system with the partial coherence interferometry (IOLMaster700) and the scheimpflug corneal topography (Pentacam). Methods: In this cross-sectional study, 146 eyes of 88 patients [mean age, (69±10) years; 62 eyes of male patients and 84 eyes of female patients] with cataract were examined before cataract extraction and IOL implantation surgery in the Tenth People's Hospital Affiliated to Tongji University from January 2016 to March 2017. Corneal curvature values acquired by the Verion optical imaging system were compared with the IOLMaster700 and the Pentacam. Keratometric data, magnitude of astigmatism, and steep astigmatic axis measurements from all three instruments were also compared. According to the steep axis of astigmatism, the eyes were divided into groups of with the rule (WTR), against the rule (ATR), and oblique astigmatism. The parameter differences between the Verion and the other devices in the three groups were analyzed. The data were evaluated using repeated measures analysis of variance and Bland-Altman plots. Results: The values of steep keratometry (Ks) of the Verion, IOLMaster700, and Pentacam were (44.60±1.32), (44.73±1.37), (44.43±1.35) D, respectively. The values of flat keratometry (Kf) of the Verion, IOLMaster700, and Pentacam were (43.51±1.41), (43.51±1.52), (43.40±1.45) D, respectively. The values of mean keratometry (Km) of the Verion, IOLMaster700, and Pentacam were (44.60±1.32), (44.12±1.35), (43.92±1.34) D, respectively. The values of astigmatism magnitude were (1.09±0.87), (1.24±1.02), (1.04±0.80) D, respectively. The F values were 1.81, 0.31, 0.93 and 2.22 in relation to Ks, Kf, Km and corneal astigmatism magnitude among the three instruments, respectively (all P>0.05). The 95% confidence intervals of Kf, Ks and astigmatism magnitude between the Verion and the other two devices were -1.10 to 0.80 D, -0.55 to 0.88 D; -1.10 D to 1.10 D, -0.80 to 1.04 D; -1.21 to 0.90 D, -0.92 to 1.02 D. The outcomes were considered acceptable. There were no statistically differences in steep astigmatic axis measurements between the Verion and the other two instruments among the WTR (62 eyes), ATR (45 eyes) and oblique (15 eyes) groups (F=0.63, 0.37; P=0.54, 0.72, respectively). Conclusions: The Verion image guided system is a reliable system for the measurement of keratometry values and astigmatism. The keratometric power, magnitude and steep axis of astigmatism have no significant difference, and there is a good agreement among the Verion, IOL Master 700, and Pentacam. (Chin J Ophthalmol, 2020, 56: 47-52).

[The rotational stability of Toric intraocular lenses and influencing factors in cataract patients with different axial length]

Objective: To evaluate the rotational stability of the Toric intraocular lens (TIOL) and influencing factors in cataract patients with different axial length. Methods: This retrospective cohort study consecutively enrolled patients who had phacoemulsification and AcrySof TIOL implantation in Peking University Third Hospital from May 2018 to January 2019. Based on axial length, patients were divided into two groups. Group A consisted of patients whose axial length was ≤ 24 mm. Patients whose axial length was >24 mm were included in group B. Data at three months postoperatively were used to evaluate the rotational stability of TIOL and its correlation with axial length, corneal white to white distance, lens thickness and TIOL spherical power. And t test, nonparametric test, chi-square test and Spearman test were used for statistical analysis. Results: Group A enrolled 39 patients (17 males and 22 females), with a median age of 74 years (range, 36-86 years). Group B enrolled 26 patients (11 males and 15 females), with a median age of 68 years (range, 36-86 years). For the efficacy of TIOL, in group A, the best corrected distance visual acuity (BCDVA, logarithm of the minimum angle of resolution) was 0.30 (0.10, 1.00) preoperatively and 0.10 (0.00, 0.60) postoperatively, and the astigmatism was 2.11 (0.95, 5.10) D preoperatively and 1.00 (0.00, 1.75) D postoperatively. In group B, the BCDVA was 0.36 (0.05, 1.00) preoperatively and 0.05 (0.00, 0.40) postoperatively, and the astigmatism was 2.00 (0.78, 3.76) D preoperatively and 0.75 (0.00, 2.25) D postoperatively. Between group A and group B, there were no significant differences in BCDVA (P=0.604) and astigmatism (P=0.789) preoperatively.In these two groups, postoperative BCDVA and astigmatism both significantly improved compared to preoperative parameters (both P<0.01). Between group A and group B, there were no significant differences in BCDVA (P=0.536) and astigmatism (P=0.076) postoperatively. In terms of rotational stability, the rotation in group A was 5.15°±3.62°, and that in group B was 6.50°±4.66°. There was no statistical difference between two groups (P=0.195). As for predictability, the percentage of eyes with rotation ≤5° was 59.0% (23 eyes) in group A and 50.0% (13 eyes) in group B. There was no statistical difference between the two groups (P=0.647). There was no significant correlation between the rotational stability of TIOL and axial length, corneal white to white distance, lens thickness or TIOL spherical power (P=0.836, 0.568, 0.170, 0.365). Conclusions: The rotational stability of TIOL at three months postoperatively in patients whose axial length >24 mm is of no difference with patients whose axial length ≤ 24 mm. It has no correlation with axial length, corneal white to white distance, lens thickness and TIOL spherical power. (Chin J Ophthalmol, 2020, 56: 41-46).

Comparison of three different diffractıve multifocal intraocular lenses with a +2.5, +3.0, and +3.75 diopter additıon power

Purpose

To compare the functional outcomes and astigmatic tolerability after implantation of multifocal intraocular lenses (IOLs) with a +2.5, +3.0, and +3.75 diopter (D) addition power.

Methods

This study included 122 eyes of 61 patients who had bilateral cataract extraction and implantation of diffractive aspheric multifocal acrylic IOLs with +2.5 D (+2.5 group), +3.0 D (+3.0 group), and +3.75 D (+3.75 group) addition powers. 1-year after surgery, distance corrected near (DNVA) and intermediate (DIVA) visual acuities at 32, 40, 45, 50, 55, and 60 cm; and contrast sensitivity measurements under photopic, mesopic and mesopic with glare conditions; spherical and astigmatic defocus testing; distance-intermediate-near vision patient satisfaction levels; spectacle dependance; patient-reported outcomes were assessed binocularly.

Results

The +2.50 D group had better DIVA than both +3.0 group and +3.75 groups at 45 cm, 50 cm, 55 cm, and 60 cm (p < 0.05). The +3.75 group had better DNVA than both +2.5 and +3.0 IOL groups at 32 cm (p < 0.05). There was no significant difference in mean contrast values at all frequencies between three IOL groups (p > 0.05). The +2.50 D group showed better astigmatic tolerability than +3.00 group (at 2.00 D) and +3.75 group (at 1.50 D, and at 2.00 D) (p < 0.05).

Conclusion

Multifocal IOLs with +2.5 add power have better intermediate vision, but worse near vision compared to multifocal IOLs with +3.00 D and +3.75 D add power. Multifocal IOLs with +2.50 D add power tend to have better astigmatic defocus tolerability than multifocal IOLs with +3.00 D and +3.75 D add powers.

The impact of exposure on the magnitude of astigmatism formed within the precorneal tear film over the central optical zone of the cornea in ocular surface disease

PURPOSE

To estimate the astigmatic power and axis of the tear film over the central optical zone of the cornea by vector analysis of topographic data, in ocular surface disease (OSD) and controls, during blink suppression.

METHODS

Video-keratoscopic images were captured on opening the eyes after a single blink 5, 10 & 15 s later during blink suppression in OSD patients (mixed aetiology, group 1 age 20 - 50 years, n = 12, group 2 > 50 years, n = 38) and controls (group 3, n = 19). The SimK and axis values were used to calculate the astigmatism (power and axis) that formed in the precorneal tear film during each period. Data were aggregated into 3 periods; T0-T5 (between 0 & 5 s after the blink), T5-T10 (5 & 10 s later, T10-T15 (between 10 & 15 s later).

RESULTS

Mean (± SD, 95%CI) astigmatic power (DC) formed in the tear film over each period was respectively : Group 1, -0.81 DC (0.99, -1.44 to -0.17), -2.65 DC(1.36, -3.52 to -1.79), -1.37 DC (2.15, -2.73 to -0.01). Group 2, -0.33 DC (0.38, -0.45 to -0.20), -0.57 DC (0.97, -0.91 to -0.24) -0.96 DC (2.10, -1.68 to -0.24), Group 3, -0.57 DC (0.55 -0.76 to -0.38), -0.56 DC (0.57, -0.76 to -0.37), -0.31 DC (0.44, -0.46 to -0.16). Changes were significant in groups 1 (p = 0.013) & 3 (p = 0.033) but not in 2 (p = 0.078). Intergroup differences were significant at all periods (p < 0.05). Significant correlations were detected following vector analysis, e.g Group2 between the astigmatism formed during T5-T10 (y) and ocular surface astigmatism at 5 s was y = 0.281x - 0.834 (r = 0.328, n = 38, p < 0.05). In all three groups apparent changes in the axes of astigmatism were not significant (p > 0.05).

CONCLUSIONS

Changes in the precorneal tear film after blinking are predominately astigmatic indicating that changes in the central region of the tear film following the natural blink are quasi-orthogonal.