Evaluation of the effectiveness of combined femtosecond laser-assisted cataract surgery and femtosecond laser astigmatic keratotomy in improving post-operative visual outcomes

Background

To determine postoperative refractive and visual outcomes and astigmatic changes after femtosecond laser astigmatic keratotomy in femtosecond laser-assisted cataract surgery (FLACS).

Methods

This was a prospective interventional case series. Patients with age-related cataract and corneal astigmatism (1.0–3.0D) were treated with FLACS and femtosecond laser astigmatic keratotomy (FSAK). All patients underwent examinations before and 3 months after surgery; visual acuity, subjective and objective refraction, and corneal astigmatism were evaluated and recorded for all patients by using an OPD-Scan III topographer. Vector analysis of astigmatic changes was performed by using the Alpins vector method.

Results

Twenty-five patients were included in the study. Postoperatively, refractive and corneal astigmatism were both reduced significantly (P < 0.05), concurrent with improved uncorrected distance visual acuity and corrected distance visual acuity. The rate of spectacle use was significantly reduced at 3 months postoperatively (P = 0.001). The mean magnitude of the target-induced astigmatism vector (1.40 ± 0.37D) was slightly higher than the mean magnitude of the surgically induced astigmatism vector (1.22 ± 0.46D). The magnitude of error (− 0.18 ± 0.36D), as well as the correction index (0.88 ± 0.29), demonstrated slight undercorrection. The angle of error was 0.85 ± 13.69°, which was close to zero.

Conclusions

Combined femtosecond laser-assisted cataract surgery and astigmatic keratotomy may be an effective approach to manage preoperative astigmatism in cataract surgery, although slight undercorrection may exist during short-term follow-up.

Trial registration

ChiCTR-TRC-14004977

Comparison between Wavefront-optimized and corneal Wavefront-guided Transepithelial photorefractive keratectomy in moderate to high astigmatism

BACKGROUND

To compare the clinical outcomes of wavefront-optimized (WFO) transepithelial photorefractive keratectomy (trans-PRK) and corneal wavefront-guided (CWFG) trans-PRK for myopic eyes with moderate to high astigmatism.

METHODS

One hundred ninety-six eyes (196 patients) with moderate to high astigmatism (≥ 1.75 D) treated with WFO or CWFG trans-PRK (101 and 95 eyes, respectively) were retrospectively registered. Safety, efficacy, predictability, vector analysis, and corneal aberrations were compared between groups preoperatively and at 6 months postoperatively.

RESULTS

At postoperative 6 months, the mean logMAR uncorrected distance visual acuity was similar in the WFO (- 0.07 ± 0.08) and CWFG (- 0.07 ± 0.07) groups. Safety, efficacy, and predictability of refractive and visual outcomes were also similar. The correction indices were 1.02 ± 0.14 and 1.03 ± 0.13 in the WFO and CWFG groups, respectively, with no significant difference. The absolute values of the angle of error were significantly higher in the WFO group (2.28 ± 2.44 vs. 1.40 ± 1.40; P = 0.002). Corneal total root mean square higher-order aberrations and corneal spherical aberrations increased postoperatively in both groups; however, the change was smaller in the CWFG group. Corneal coma showed a significant increase postoperatively only in the WFO group.

CONCLUSIONS

WFO and CWFG trans-PRK are safe and effective for correcting moderate to high astigmatism. However, CWFG trans-PRK provides a more predictable astigmatism correction axis and fewer induced corneal aberrations.

Spectacle prescriptions review to determine prevalence of ametropia and coverage of frequent replacement soft toric contact lenses

PURPOSE

To determine the prevalence of ametropia and astigmatism in a clinic population and to estimate the coverage of frequent replacement soft toric lenses.

METHODS

A review of patient files was conducted at three clinical sites. Prescription data collected between January 2014 and March 2017 in a patient cohort 14 to 70 years of age inclusive were analyzed to determine prevalence of ametropia and astigmatism. The percent coverage of frequent replacement soft toric contact lenses has further been estimated using different ranges for sphere, cylinder and axis availability.

RESULTS

In total 101,973 patients were included in the analysis of which 69.5% were considered myopic, 26.9% hyperopic and 3.5% emmetropic as determined by the eye with the larger absolute value of the spherical equivalent refraction. Astigmatism in at least one eye was found in 87.2% of the population, with 37.0% of the patients exhibiting astigmatism of at least -1.00DC in at least one eye. With-the-rule astigmatism was most prevalent in the 14 to 20 year-olds (53.0%), while against-the-rule astigmatism was most prevalent in the 41 to 70 year-olds (50.7%). For astigmatic eyes with a cylinder of at least -0.75DC (n = 83,540; 41% of all eyes), the coverage with toric soft lenses varied greatly depending on parameter availability and ranged between 30.7% (sphere: Plano to -3.00D, cylinder: up to -1.75DC, axes: 90 ± 10° and 180 ± 10°) and 96.4% (sphere: + 6.00D to -10.00D, cylinders: up to -2.75DC, 18 axes).

CONCLUSION

Currently available frequent replacement soft toric contact lenses provide coverage for up to 96.4% of potential patients.

Surgical technique for management of isolated lenticular coloboma with high corneal astigmatism

We describe a surgical technique for the correction of isolated congenital lenticular coloboma associated with high corneal astigmatism. Transscleral fixation of the capsular bag with a single eyelet Cionni capsular tension ring was followed by in-the-bag implantation of a toric intraocular lens (IOL). This lead to complete correction of the lenticular defect and perfect alignment of the toric lens. In this case, the child attained an unaided distance visual acuity of 20/30 following amblyopia therapy and a well-aligned toric IOL at 12 months of follow-up. This technique can be used in cases with concomitant lenticular coloboma and significant corneal astigmatism.

Visual Outcomes and Higher Order Aberrations Following LASIK on Eyes with Low Myopia and Astigmatism

Background:

Laser-Assisted in situ Keratomileusis (LASIK) can induce corneal aberrations that can impact vision and patient satisfaction. Recent developments in laser technologies have helped minimise these aberrations.

Objective:

To assess the quality of vision and change in Higher-Order Aberrations (HOAs) following wavefront-optimized LASIK in low-myopic astigmatic patients.

Methods:

LASIK was performed on a total of 76 eyes in patients with myopia <4.0 D and cylinder <2.0 D using the WaveLight® EX500 excimer and FS200 femtosecond laser platform. Visual acuity, contrast sensitivity and HOAs were measured at 1 and 3 months postoperatively and compared to preoperative values. Subjective quality of vision was assessed pre- and postoperatively using a VF14 questionnaire.

Results:

Mean postoperative Spherical Equivalent (SE) was -0.09 ± 0.26 µm with 95% of patients within ± 0.5 D of attempted SE. Postoperative uncorrected distance visual acuity was 20/20 or better for 96% of patients. Contrast sensitivity increased against horizontal and vertical gratings at all spatial frequencies except for vertical gratings at 18 cycles/degree. Spherical aberration and total HOA increased by 0.085 µm and 0.13 µm respectively. The mean VF14 score increased from 89.2 ± 16.7% to 99 ± 1.4% postoperatively.

Conclusion:

LASIK performed using the WaveLight® EX500 excimer and WaveLight® FS200 laser platform provided improved contrast sensitivity and visual acuity with minimal introduction of HOAs, making it a suitable platform for low myopic astigmatic patients.

Comparison of Anterior, Posterior, and Total Corneal Astigmatism Measured Using a Single Scheimpflug Camera in Healthy and Keratoconus Eyes

Purpose

To compare the effect of posterior corneal astigmatism on the estimation of total corneal astigmatism using anterior corneal measurements (simulated keratometry [K]) between eyes with keratoconus and healthy eyes.

Methods

Thirty-three eyes of 33 patients with keratoconus of grade I or II and 33 eyes of 33 age- and sex-matched healthy control subjects were enrolled. Anterior, posterior, and total corneal cylinder powers and flat meridians measured by a single Scheimpflug camera were analyzed. The difference in corneal astigmatism between the simulated K and total cornea was evaluated.

Results

The mean anterior, posterior, and total corneal cylinder powers of the keratoconus group (4.37 ± 1.73, 0.95 ± 0.39, and 4.36 ± 1.74 cylinder diopters [CD], respectively) were significantly greater than those of the control group (1.10 ± 0.68, 0.39 ± 0.18, and 0.97 ± 0.63 CD, respectively). The cylinder power difference between the simulated K and total cornea was positively correlated with the posterior corneal cylinder power and negatively correlated with the absolute flat meridian difference between the simulated K and total cornea in both groups. The mean magnitude of the vector difference between the astigmatism of the simulated K and total cornea of the keratoconus group (0.67 ± 0.67 CD) was significantly larger than that of the control group (0.28 ± 0.12 CD).

Conclusions

Eyes with keratoconus had greater estimation errors of total corneal astigmatism based on anterior corneal measurement than did healthy eyes. Posterior corneal surface measurement should be more emphasized to determine the total corneal astigmatism in eyes with keratoconus.

Comparative evaluation of rotational stability and visual outcome of toric intraocular lenses with and without a capsular tension ring

Purpose:

To evaluate the rotational stability of toric intraocular lens (IOL) when co-implanted with a capsular tension ring (CTR) as compared to that of a toric IOL without a CTR.

Methods:

This was a prospective randomized clinical trial performed in a tertiary care centre in India. Fifty adult human eyes with visually significant cataract and regular corneal astigmatism ≥1.5D divided into two groups of 25 eyes each, A and B by simple randomization. Eyes with corneal pathology, lens subluxation, and a specular endothelial cell count <2000/mm² were excluded from the study. The eyes in both the groups underwent standard phacoemulsification and were implanted with a toric IOL. In Group A, a CTR was put in the bag before IOL implantation. The groups were called for follow-up on day 1, 1 week, 1 month, and 3 months, postoperatively. The axis of the toric IOL on each visit was measured by slit lamp imaging in retroillumination and analyzed digitally.

Results:

Mean rotation of toric IOL at 3 months postoperatively was 1.85 ± 1.72° in Group A and 4.02 ± 2.04° in Group B. The difference was statistically significant (P = 0.003).

Conclusion:

Coimplantation of a CTR is a safe and effective technique for ensuring better rotational stability of toric IOLs.

[Value the correction of corneal astigmatism in cataract surgery]

The aim of modern micro-incision phacoemulsification combined with foldable intraocular lens implantation and femtosecond laser-assisted cataract surgery is evolving from a simple pursuit of recuperation to a refractive procedure, which involves the correction of ametropia according to preoperative and postoperative refractive conditions, especially corneal astigmatism, in order to achieve the goal of optimized postoperative uncorrected full range of vision. Nowadays, due attention to the effect of preoperative corneal astigmatism, surgery-induced astigmatism and residual astigmatism after operation is lacked, which affect postoperative visual acuity significantly. There are many effective ways to reduce corneal astigmatism after cataract surgery including selecting appropriate size and location of clear corneal incision, employing astigmatism keratotomy and the implantation of Toric intraocular lenses, which need to be appropriately applied and popularized. At the same time, surgical indications, predictability and safety should also be taken into account.(Chin J Ophthalmol, 2018, 54: 321-323).

Clinical outcomes of Transepithelial photorefractive keratectomy to treat low to moderate myopic astigmatism

Background

To evaluate the refractive and visual outcomes of Transepithelial photorefractive keratectomy (TransPRK) in the treatment of low to moderate myopic astigmatism.

Methods

This retrospective study enrolled a total of 47 eyes that had undergone Transepithelial photorefractive keratectomy. Preoperative cylinder diopters ranged from − 0.75D to − 2.25D (mean − 1.11 ± 0.40D), and the sphere was between − 1.50D to − 5.75D. Visual outcomes and vector analysis of astigmatism that included error ratio (ER), correction ratio (CR), error of magnitude (EM) and error of angle (EA) were evaluated.

Results

At 6 months after TransPRK, all eyes had an uncorrected distance visual acuity of 20/20 or better, no eyes lost ≥2 lines of corrected distant visual acuity (CDVA), and 93.6% had residual refractive cylinder within ±0.50D of intended correction. On vector analysis, the mean correction ratio for refractive cylinder was 1.03 ± 0.30. The mean error magnitude was − 0.04 ± 0.36. The mean error of angle was 0.44° ± 7.42°and 80.9% of eyes had axis shift within ±10°. The absolute astigmatic error of magnitude was statistically significantly correlated with the intended cylinder correction (r = 0.48, P < 0.01).

Conclusions

TransPRK showed safe, effective and predictable results in the correction of low to moderate astigmatism and myopia.

Relative Proportion Of Different Types Of Refractive Errors In Subjects Seeking Laser Vision Correction

Background:

Refractive errors are a form of optical defect affecting more than 2.3 billion people worldwide. As refractive errors are a major contributor of mild to moderate vision impairment, assessment of their relative proportion would be helpful in the strategic planning of health programs.

Purpose:

To determine the pattern of the relative proportion of types of refractive errors among the adult candidates seeking laser assisted refractive correction in a private clinic setting in Saudi Arabia.

Methods:

The clinical charts of 687 patients (1374 eyes) with mean age 27.6 ± 7.5 years who desired laser vision correction and underwent a pre-LASIK work-up were reviewed retrospectively. Refractive errors were classified as myopia, hyperopia and astigmatism. Manifest refraction spherical equivalent (MRSE) was applied to define refractive errors.

Outcome Measures:

Distribution percentage of different types of refractive errors; myopia, hyperopia and astigmatism.

Results:

The mean spherical equivalent for 1374 eyes was -3.11 ± 2.88 D. Of the total 1374 eyes, 91.8% (n = 1262) eyes had myopia, 4.7% (n = 65) eyes had hyperopia and 3.4% (n = 47) had emmetropia with astigmatism. Distribution percentage of astigmatism (cylinder error of ≥ 0.50 D) was 78.5% (1078/1374 eyes); of which % 69.1% (994/1374) had low to moderate astigmatism and 9.4% (129/1374) had high astigmatism.

Conclusion and Relevance:

Of the adult candidates seeking laser refractive correction in a private setting in Saudi Arabia, myopia represented greatest burden with more than 90% myopic eyes, compared to hyperopia in nearly 5% eyes. Astigmatism was present in more than 78% eyes.

A clinical study to evaluate the results after toric intraocular lens implantation in cases of corneal astigmatism

Backgroud

Modern day cataract surgery aims at a spectacle free vision which becomes difficult in cases with pre-operative astigmatism more than 1.5 D. Implantation of toric intra-ocular lenses (IOL) after phacoemulsification in such eyes is one of the ways to counteract this problem.

Methods

Thirty eyes with pre-operative astigmatism between 1.5 D and 4.5 D were implanted with toric IOLs following uneventful phaco-emulsification. The estimation of the axis of implantation of this toric IOL included calculating the surgically induced astigmatism (SIA) of the surgeon.

Results

Post-operatively, 20 (66.67%) patients had a visual acuity 6/9 or better and 17 (57%) had a visual acuity of 6/6 at 12 weeks. The mean postoperative uncorrected visual acuity (UCVA) was 0.12 ± 0.15 at 12 weeks. The difference between means of preoperative best corrected visual acuity (BCVA) LogMAR and postoperative UCVA at 12 wk LogMAR was found to be statistically significant at p = 0.001. Mean (SD) scores of pre-op astigmatism of study group was -2.20 (0.67) and residual astigmatism was -0.32 (0.44).

Conclusions

The difference between means of pre-op astigmatism and residual astigmatism in the study group was significant at p = 0.001 with 95% CI -2.22 to -1.50. This significant difference was because of the toric IOL implantation.

[Refractive outcomes and precision in toric intraocular lens alignment using an automated alignment system]

PURPOSE

To compare precision in toric intraocular lens (TIOL) alignment and refractive outcomes between an intraoperative automated digital marker system and the conventional manual-ink marking.

MATERIALS AND METHODS

Prospective single center study including consecutive patients undergoing uneventful cataract surgery with corneal astigmatism greater than 1 diopter. Total corneal astigmatism was measured using a placido-dual Scheimpflug system (GalileiG4^®, Ziemer). Acrysof^® SN6AT (Alcon) TIOL's were implanted, and patients were divided into 2 groups, the digital group (Verion^®, Alcon) and the ink-marking group (Pendular marker, AMO). Mean error in TIOL axis, visual acuity and residual astigmatism were analyzed at 3 days, one month and 6 months after surgery.

RESULTS

In total, 45 eyes of 30 patients were included (n=25 digital group, n=20 ink-marking group). The mean preoperative total corneal astigmatism was 1.71±0.53 diopters. At one month, there was a significantly lower mean average error in TIOL axis in the digital group compared to the ink-marking group (2.6±2.3° and 6.4±2.8° respectively, P=0.009). At 6months, these results remained statistically significant. Mean residual astigmatism was 0.7±0.4 diopters at one month, without significant difference between the two groups (P=0.9). The rate of misalignment less than or equal to 5° was 86 % (n=25) in the digital group and 63 % (n=20) in the ink-marking group (P=0.05).

CONCLUSION

Intraoperative digital marker system is associated with better TIOL alignment accuracy and better reproducibility than the manual ink-marking method.

Analysis of corneal astigmatism with NIDEK axial length scan in caucasian cataract surgery candidates

Aims and Objectives

The aim of the study was to analyze and quantify the pattern of corneal astigmatism in Caucasian cataract surgery patients using a new optical biometer (axial length [AL] Scan, NIDEK Co., Gamagori, Japan).

Patients and Methods

The datasets of cataract surgery patients acquired between March 1, 2014, and April 15, 2016, were collected and analyzed. The corneal power (flat keratometry, steep keratometry, and mean keratometry), negative cylinder power, and axis of astigmatism were recorded. Keratometry values were optically measured by optical low coherence interferometry (AL-Scan, NIDEK Co., Ltd.,) before cataract extraction.

Results

The study comprised 1233 eyes of 838 consecutive cataract candidates with a mean age of 66.8 ± 10.7 years (range 40-97 years). The mean keratometry value and corneal astigmatism were 43.69 ± 1.61 D and 0.84 ± 0.70 D, respectively. Corneal astigmatism of 1.00 D or greater was found in 344 eyes (27.9%), and 548 eyes (44.4%) had against-the-rule astigmatism. A trend toward decreasing J0 and J45 with age was found by linear regression models. The per-year increase in age was associated with a J0 and J45 decrease of 0.002 D and 0.001D, respectively.

Conclusion

This study provides the distribution of astigmatism axis and power for cataract patients in age subsets from Turkey.

[Riboflavin UVA crosslinking in progressive keratoconus]

In patients with keratoconus, a progressive, ectatic disease of the cornea, the shape of the cornea is continuously changing leading to a reduction in visual acuity by progressive myopia and more and more (irregular) astigmatism. The symptomatic treatment consists of the prescription of glasses or special gas-permeable rigid contact lenses. Corneal tomography is generally used for diagnosis. After initial diagnosis of keratoconus, regular tomographic follow-ups should be performed. If clinically significant progression is found and confirmed by repeated measurements, riboflavin UVA collagen crosslinking should be offered to the patients. The aim of riboflavin UVA collagen crosslinking is to halt the progression of the disease to avoid further complications. The therapeutic principle is a combined effect of the photosensitizer riboflavin and UVA light. This stiffening effect of the corneal tissue halts the progression of keratoconus. The efficacy of this treatment has been demonstrated in various randomized, controlled trials.

Astigmatism in Chinese primary school children: prevalence, change, and effect on myopic shift

PURPOSE

To study the prevalence, type, and progression of astigmatism in primary school children, and its effect on myopic shift.

STUDY DESIGN

A prospective study carried out in a primary school in southern Taiwan.

METHODS

The study was performed on a subset of children, one year after initial examination. Refractive error measured by cycloplegic autorefraction was the main study outcome. Astigmatism was recorded as negative cylinder form, and we defined clinical significant astigmatism (CSA) as cylinder refraction -1.0 D or greater. Myopia was defined as a spherical equivalent refraction (SER) of -0.50 D or greater.

RESULTS

Three hundred sixty-two children, mean age was 8.97 y/o (SD 1.41; range 7 to 11 y/o) participated in the study. One hundred nineteen (32.9 %) subjects had CSA at the initial screening. The mean cylinder refraction was -0.80 + 0.84 diopters (D) (-5.25 D to 0.00 D), with predominant with rule astigmatism (69.7%). In the 183 children studied longitudinally, the mean cylinder refraction was reduced from -0.74 D to -0.58 D (p< 0.05). The cylinder refraction in the initial CSA group was not associated with SER change (p=0.99) or axial length change (p=0.55). Compared to the initial non-CSA group, the initial CSA group had no significant difference in axial length elongation (p=0.20).

CONCLUSION

The prevalence of astigmatism was not low in the Chinese primary school children and with-the-rule astigmatism was predominant. The astigmatism decreased during the 1 year follow-up. The CSA was not associated with myopia progression (p=0.99).

[Toric lens implantation in cataract surgery: Automatic versus manual horizontal axis marking, analysis of 50 cases]

SUBJECT

The main objective of our study is to evaluate the contribution of automated conjunctival recognition in the alignment of toric implants by comparing the automatic alignment optimized with Callisto™ to the manual marking of the horizontal axis.

MATERIALS AND METHODS

We performed a prospective, descriptive, and monocentric study on patients undergoing cataract surgery with toric implantation (Asphina 709 Zeiss), operated by a surgeon with good experience in toricity, between September 2016 and March 2017. We analyzed the agreement between the manual marking of the 0°-180° axis versus the one automatically generated by the Callisto™, as well as the alignment of the IOL and the refractive results at 1 month.

RESULTS

We included 50 eyes of 26 patients. The corrected mean astigmatism was 1.9 D. The mean difference between the 2 axes was 4.7° [0°-12.3°]. Only 50 % of the preoperative manual markings were consistent with the automatic measurement (<5°). At one month, the average rotation recorded was 4.3° [0°-29°]. The alignment was identical for 70 % (n=35) of the IOL (≤5°). As for residual subjective astigmatism, it was on average 0.58 D. The mean visual acuity without correction was 8/10 and 55 % had 10/10 without correction.

DISCUSSION

The refractive performance depends on the preoperative measurement, the correct alignment of the IOL and its stability in the bag. Our study shows the value of automatic conjunctival recognition in the determination of the axis of peroperative alignment, even in an experienced operator. This precision is essential for a good refractive result, especially since the residual astigmatism in case of misalignment will increase with the power of the implant.

CONCLUSION

Our study shows excellent refractive results, whatever the initial astigmatism, using the automatic alignment. The precision of the toric implantation opens the way to the toric multifocal implantation under the best conditions.

Refractive errors among patients attending the ophthalmology department of a medical college in North-East India

Purpose:

To determine the magnitude and pattern of refractive errors among patients attending the ophthalmology department of a new medical college in North-East India.

Materials and Methods:

A prospective study of the new patients (age ≥5 years), who were phakic and whose unaided visual acuities were worse than 20/20 but improved with pinhole, was done. Complete ophthalmic examination and refraction with appropriate cycloplegia for age were done for the 4582 eligible patients. Spherical equivalents (SE) of refractive errors of the right eyes were used for analysis.

Results:

Of the 4582 eligible patients, 2546 patients had refractive errors (55.56%). The proportion of emmetropia (SE − 0.50–+0.50 diopter sphere [DS]), myopia (SE <−0.50 DS), high myopia (SE >−5.0 DS), and hypermetropia (>+0.50 DS for adults and >+2.0 DS for children) were 53.1%, 27.4%, 2.6%, and 16.9%, respectively. The proportion of hyperopia increased till 59 years and then decreased with age (P = 0.000). The proportion of myopia and high myopia decreased significantly with age after 39 years (P = 0.000 and P = 0.004, respectively). Of the 1510 patients with astigmatism, 17% had with-the-rule (WTR), 23.4% had against-the-rule (ATR), and 19% had oblique astigmatisms. The proportion of WTR and ATR astigmatisms significantly decreased (P = 0.000) and increased (P = 0.000) with age, respectively.

Conclusions:

This study has provided the magnitude and pattern of refractive errors in the study population. It will serve as the initial step for conducting community-based studies on the prevalence of refractive errors in this part of the country since such data are lacking from this region. Moreover, this study will help the primary care physicians to have an overview of the magnitude and pattern of refractive errors presenting to a health-care center as refractive error is an established and significant public health problem worldwide.

Corneal functional optical zone under monocular and binocular assessment

BACKGROUND

In this retrospective randomized case series, we compared bilateral symmetry between OD and OS eyes, intercorneal differences and Functional Optical Zone (FOZ) of the corneal aberrations.

METHODS

Sixty-seven normal subjects (with no ocular pathology) who never had any ocular surgery were bilaterally evaluated at Augenzentrum Recklinghausen (Germany). In all cases, standard examinations and corneal wavefront topography (OPTIKON Scout) were performed. The OD/OS bilateral symmetry was evaluated for corneal wavefront aberrations, and FOZ-values were evaluated from the Root-Mean-Square (RMS) of High-Order Wavefront-Aberration (HOWAb). Moreover, correlations of FOZ, spherical equivalent (SE), astigmatism power, and cardinal and oblique astigmatism for binocular vs. monocular, and binocular vs. intercorneal differences were analyzed.

RESULTS

Mean FOZ was 6.56 ± 1.13 mm monocularly, 6.97 ± 1.34 mm binocularly, and 7.64 ± 1.30 mm intercorneal difference, with all strongly positively correlated, showing that the diameter of glare-free vision is larger in binocular than monocular conditions. Mean SE was 0.78 ± 1.30 D, and the mean astigmatism power (magnitude) was 0.46 ± 0.52 D binocularly. The corresponding monocular values for these metrics were 0.78 ± 1.30 D and 0.53 ± 0.53 D respectively. SE, astigmatism magnitude, cardinal astigmatism component, and FOZ showed a strong correlation and even symmetry; and oblique astigmatism component showed odd symmetry indicating Enantiomorphism between the left and right eye.

CONCLUSIONS

These results confirm OD-vs.-OS bilateral symmetry (which influences binocular summation) of HOWAb, FOZ, defocus, astigmatism power, and cardinal and oblique astigmatism. Binocular Functional Optical Zone calculated from corneal wavefront aberrations can be used to optimize refractive surgery design.

Real-world refractive outcomes of toric intraocular lens implantation in a United Kingdom National Health Service setting

BACKGROUND

With increasing availability of toric intraocular lenses (IOL) for cataract surgery, real-world refractive outcome data is needed to aid the counselling of patients regarding lens choice. We aim to assess the outcomes of toric intraocular lens use in the non-specialist environment of a typical United Kingdom NHS cataract service.

METHODS

A retrospective cohort study conducted at the Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, UK. All patients who received a toric IOL implant over a 10 months period. Patients underwent pre-operative corneal marking, phacoemulsification and toric IOL implantation. Biometry was obtained using a Zeiss IOLMaster 500 and the toric IOLs were selected using the manufacturers' online calculators. Post-operative refractions were obtained from optometrist's manifest refraction or by autorefraction. The outcome measures were post-operative unaided visual acuity (UVA), spherical equivalent refraction, cylindrical correction and all complications.

RESULTS

Thirty-two eyes of 24 patients aged 21-86 years (mean 66.4, SD 14.5) were included. UVA was superior to pre-operative best-corrected visual acuity (BCVA) in 81% of eyes, same in 16% and inferior in 3%, resulting in a median improvement of 0.20 LogMAR (IQR 0.10 to 0.30). 56%, 81%, 94% and 100% of eyes were within ±0.5, ±1.0, ±1.5 and ±2.0 D of predicted spherical equivalent, respectively. Three (9%) eyes required further surgery to rectify significant IOL rotation.

CONCLUSIONS

Reduced cylindrical correction and improved UVA could be expected in the majority of patients undergoing toric IOL implantation. Patients should be counselled about the risk of lens rotation.

Toric intraocular lens outcomes with a new protocol for IOL selection and implantation

INTRODUCTION

The published literature on toric intraocular lenses (IOL) reports postoperative refractive cylinder less than or equal to 0.5 D in anywhere from 25% to 100% of implantations with both the Acrysof^® Toric and Tecnis^® Toric IOL, depending upon the article. However, the majority of articles tend to cite rates between 70% and 80%.

PURPOSE

The purpose was to evaluate my personal outcomes for both models of toric IOL, in terms of one-month postoperative refractive cylinder, after implementation of new methods of IOL selection, calculation and implantation.

MATERIALS AND METHODS

The new protocol included measurement of centroid surgically induced astigmatism by vector analysis; calculations using only the Barrett toric calculator, for which the keratometry values were obtained by optical biometry, while the keratometric axes were chosen by visual inspection of the axial topographic map; preoperative marking with the toriCAM cell phone appliance; and corneal incisions performed either manually or with a femtosecond laser. A prospective, observational study was conducted of all consecutive monofocal toric IOL implantations from September 2016 through April 2017. One-month postoperative refractive cylinder was recorded for each eye.

RESULTS

Seventy eyes were implanted with monofocal toric IOL, 31 Acrysof^® Toric and 39 Tecnis^® Toric. Mean postoperative refractive cylinder was 0.48 D (0.00-1.50) for the Acrysof^® Toric group and 0.46 D (0.00-1.00) for the Tecnis^® Toric group. There were no statistically significant differences in postoperative refractive cylinder between IOL models or methods of incision. The percentage of eyes achieving postoperative refractive cylinder ≤0.50 D ("success") was 77% for the Acrysof^® Toric group (82% for laser-assisted and 75% for manual) and 72% for the Tecnis^® Toric group (80% for laser-assisted and 69% for manual).

CONCLUSION

The implementation of the new protocol resulted in an overall surgical success rate of 77% for Acrysof^® Toric IOL and 72% for Tecnis^® Toric IOL (P=0.7702). Femtosecond laser-assisted surgery resulted in higher success rates than manual surgery (82% vs. 75% for Acrysof^® Toric and 80% vs. 69% for Tecnis^® Toric), but these differences were not statistically significant (Acrysof^® Toric P=0.7336; Tecnis^® Toric P=0.8862).

Changes in refractive characteristics in Japanese children with Down syndrome

PURPOSE

To investigate the refractive characteristics of Japanese children with Down syndrome.

STUDY DESIGN

Retrospective study.

METHODS

The clinical records of refractive errors and ocular manifestations in children with Down syndrome who visited the Aichi Children's Health and Medical Center between November 2001 and January 2016 were retrospectively reviewed. The children were divided into the 3 following groups depending on their age: group 1 (≤ 6 years), group 2 (7-12 years), and group 3 (13-19 years). The collection of refractive error data was performed only for the right eyes and only once for each child, when the children were last examined with their pupils dilated.

RESULTS

The study included 416 children (224 boys, 192 girls; average age, 6.1 ± 4.1 years). Group 3 had significantly stronger myopia than did groups 1 and 2. The mean cylindrical power in all the children was - 2.1 ± 1.2 diopters (D), and cylindrical power ≤ - 1.0 D (stronger than - 1.0 D) was seen in 366 eyes (88%). No significant difference in cylindrical power was found among the 3 groups.

CONCLUSIONS

The spherical equivalent refraction showed an age-dependent myopic shift. Given that the amount of astigmatism did not show age-dependent differences, the age-dependent myopic shift could be due mainly to the change in spherical power.

Temporary Haptic Externalization and Four-point Fixation of Intraocular Lens in Scleral Fixation to Enhance Stability

PURPOSE

To report the results of a new technique for intraocular lens scleral fixation of temporary haptic externalization and four-point fixation for enhanced stability.

METHODS

Two 10-0 polypropylene strands were fixed at two points 2 mm apart on each haptic of a conventional three-piece intraocular lens, using our previously reported method of temporary haptic externalization after injector implantation. Postoperative refractive outcome and stability were evaluated.

RESULTS

Although the intraocular lens was fixed at a total of four points, no intraoperative difficulties were observed during the process. Patients showed successful fixation of the intraocular lens postoperatively. The fixed intraocular lens showed good centering and minimal tilting. When compared to the two-point fixation technique, postoperative astigmatism was significantly smaller in the four-point fixation group (1.80 ± 0.84 vs. 1.00 ± 0.0.50, p = 0.033). Lens-induced astigmatism calculated from subtraction of corneal astigmatism from total astigmatism was also significantly smaller in the four-point fixation group (2.23 ± 0.98 vs.1.17 ± 0.0.70, p = 0.043). No postoperative complications were identified during a mean follow-up period of 14.8 months (range, 10 to 19 months).

CONCLUSIONS

By fixing the intraocular lens at two points on each side of the haptics, this method minimizes the tilting of the intraocular lens and thus decreases postoperative lens-induced astigmatism. Also, the possibility of intraocular lens dislocation in the long term might be decreased by this two-point fixation technique.

Toric lens implantation in cataract surgery: Automated versus manual horizontal axis marking, analysis of 50 cases

SUBJECT

The main objective of our study was to evaluate the contribution of automated conjunctival registration in the alignment of toric intraocular lenses by comparing automated registration optimized with Callisto^® to manual marking of the horizontal axis.

MATERIALS AND METHODS

We performed a prospective, descriptive, monocentric study on patients undergoing cataract surgery with a toric intraocular lens (Asphina 709 Zeiss), performed by a surgeon with good experience in toric implants, between September 2016 and March 2017. We analyzed the agreement between the manual marking of the 0-180° axis versus the one automatically generated by the Callisto™, as well as the alignment of the IOL and the refractive results at 1 month.

RESULTS

We included 50 eyes of 38 patients. The mean corrected astigmatism was 1,9 D. The mean difference between the 2 axes was 4,7° [0-12.3°]. Only 50 % of the preoperative manual markings were consistent with the automated measurement (<5°). At one month, the mean rotation recorded was 4,3° [0-29°]. The alignment was identical for 70 % (n=35) of the IOLs (≤5°). As for residual subjective astigmatism, the mean was 0.58 D. The mean visual acuity without correction was 8/10 and 55 % saw 10/10 without correction.

DISCUSSION

Refractive performance depends on preoperative measurement, correct alignment of the IOL and its stability in the bag. Our study shows the value of automated conjunctival registration in the determination of the intraoperative axis of alignment, even with an experienced surgeon. This precision is essential for a good refractive result, especially since residual astigmatism in the case of misalignment will increase with the power of the implant.

CONCLUSION

Our study shows excellent refractive results, regardless of the initial astigmatism, using automated alignment. Precision of toric implantation opens the way to toric multifocal implantation under the best conditions.

Pattern of refractive errors in Buraydah. How serious is the problem?

OBJECTIVE

The incidence of refractive errors is on the rise globally. This study was done to assess the pattern and prevalence of various errors of refraction including myopia, hypermetropia, and astigmatism in Qassim region of Saudi Arabia.

METHODS

This is a cross-sectional study conducted in Buraydah city during January 2015. The participants consisted of 188 subjects of both sexes ranging from 2 to 75 years in a shopping mall picked randomly regardless of age and gender. The study subjects were picked up from a temporary eye clinic established for 2 days in a busy shopping mall in Qassim. The refraction was performed on those patients who were willing for the examination and gave consent to be inducted in the study. Those who had any sort of refractive disorders were assessed and classified by the kind of refractive error.

RESULTS

The incidence of refractive errors was found to be reasonably high among general population regardless of gender; however, increasing age was found to be associated with increasing incidence. We found myopia as the most common error of refraction found in 91 (48.40%) study subjects, while astigmatism and hypermetropia were other errors detected.

CONCLUSIONS

Refractive errors are one of the main reasons of treatable visual impairment in youth. There is a need of standard vision testing in young population to diagnose any such problem at an early stage.

Characteristics of Posterior Corneal Astigmatism in Different Stages of Keratoconus

Purpose

To evaluate the magnitudes and axis orientation of anterior corneal astigmatism (ACA) and posterior corneal astigmatism (PCA), the ratio of ACA to PCA, and the correlation between ACA and PCA in the different stages of keratoconus (KCN).

Methods

This retrospective case series comprised 161 eyes of 161 patients with KCN (104 men, 57 women; mean age, 22.35 ± 6.10 years). The participants were divided into four subgroups according to the Amsler-Krumeich classification. A Scheimpflug imaging system was used to measure the magnitude and axis orientation of ACA and PCA. The posterior-anterior corneal astigmatism ratio was also calculated. The results were compared among different subgroups.

Results

The average amounts of anterior, posterior, and total corneal astigmatism were 4.08 ± 2.21 diopters (D), 0.86 ± 0.46 D, and 3.50 ± 1.94 D, respectively. With-the-rule, against-the-rule, and oblique astigmatisms of the posterior surface of the cornea were found in 61 eyes (37.9%), 67 eyes (41.6%), and 33 eyes (20.5%), respectively; corresponding figures in the anterior corneal surface were 55 eyes (32.4%), 56 eyes (34.8%), and 50 eyes (31.1%), respectively. A strong correlation (P ≤ 0.001, r = 0.839) was found between ACA and PCA in the different stages of KCN; the correlation was weaker in eyes with grade 3 (P ≤ 0.001, r = 0.711) and grade 4 (P ≤ 0.001, r = 0.717) KCN. The maximum posterior-anterior corneal astigmatism ratio (PCA/ACA, 0.246) was found in patients with stage 1 KCN.

Conclusion

Corneal astigmatism in anterior surface was more affected than posterior surface by increasing in the KCN severity, although PCA was more affected than ACA in an early stage of KCN.