Optimising curve fitting techniques to look for standardisation of the analysis of defocus curves derived from multifocal intraocular lenses.

INTRODUCTION: To establish the most appropriate curve fitting method to allow accurate comparison of defocus curves derived from intraocular lenses (IOLs). METHODS: Defocus curves were plotted in five IOL groups (monofocal, extended depth of focus, refractive bifocal, diffractive bifocal and trifocal). Polynomial curves from 2nd to 11th order and cubic splines were fitted. Goodness of fit (GOF) was assessed using five methods: least squares, coefficient of determination (R2adj ), Akaike information criteria (AIC), visual inspection and Snedecor and Cochran. Additional defocus steps at -2.25 D and -2.75 D were measured and compared to the calculated visual acuity (VA) values. Area under the defocus curve and range of focus were also compared. RESULTS: Goodness of fit demonstrated variable results, with more lenient methods such as R2adj leading to overfitting and conservative methods such as AIC resulting in underfitting. Furthermore, conservative methods diminished the inflection points resulting in an underestimation of VA. Polynomial of at least 8th order was required for comparison of area methods, but overfitted the EDoF and monofocal groups; the spline curve was consistent for all IOLs and methods. CONCLUSIONS: This study demonstrates the inherent difficulty of selecting a single polynomial function. The R2 method can be used cautiously along with visual inspection to guard against overfitting. Spline curves are suitable for all IOLs, guarding against the issues of overfitting. Therefore, for analysis of the defocus profile of IOLs, the fitting of a spline curves is advocated and should be used wherever possible.

High Astigmatism After Conventional Diameter Deep Anterior Lamellar Keratoplasty in Keratoconus Can Be Successfully Managed With Repeat Wide Diameter Deep Anterior Lamellar Keratoplasty.

PURPOSE: The aim of this study was to describe a new surgical technique to replace a conventional diameter (≤8 mm) deep anterior lamellar keratoplasty (DALK) graft with associated high astigmatism refractory to corneal-based astigmatic procedure/intolerance to contact lenses with a larger diameter (≥9 mm) DALK graft to improve best spectacle-corrected visual acuity (BSCVA). METHODS: Two eyes from 2 keratoconic patients at Southend University Hospital between December 2019 and June 2021 with a minimum follow-up of 17 months were evaluated. The primary outcome of interest was Snellen BSCVA with a secondary outcome of topographic cylinder. RESULTS: Patient 1 had undergone initial 8 mm diameter DALK, with residual keratometric astigmatism of nearly 12 diopters (D) postoperatively despite numerous astigmatic interventions, with a BSCVA of 6/60, before undergoing 9 mm diameter repeat modified DALK. After suture removal and subsequent in-the-wound blunt manual relaxing incisions, the patient had a final keratometric astigmatism of 3.5 D, manifest refraction of plano/-3.50 × 175, and a BSCVA of 6/9. Patient 2 had undergone initial 7.75 mm diameter DALK, with residual keratometric astigmatism of 10.5 D with a BSCVA of counting fingers. The patient underwent 9 mm repeat modified DALK with final residual keratometric astigmatism of 3.1 D after suture removal, manifest refraction of -1.00/-2.75 × 25, and BSCVA of 6/9. CONCLUSIONS: Wide diameter DALK (>9 mm) is effective in the management of conventional diameter DALK (≤8 mm) associated high astigmatism in keratoconus. Creation of a peripheral posterior stromal shoulder also allows safe further titration of residual astigmatism if needed.

Intravitreal dexamethasone to manage post endothelial keratoplasty cystoid macular oedema refractory to topical therapy.

BACKGROUND/OBJECTIVES: To describe the visual and clinical outcomes of patients with post endothelial keratoplasty (EK) cystoid macular oedema (CMO) refractory to topical treatment with intravitreal sustained-release dexamethasone implant (Ozurdex). SUBJECTS/METHODS: 131 eyes from 111 patients undergoing solitary or combined EK (52 DSAEK (40.0%) and 79 DMEK (60.0%)) at Southend University Hospital between January 2020 and February 2022 with a minimum follow-up of 6 months were evaluated. Patients suspected of having CMO underwent spectral-domain macular optical coherence tomography (SD-OCT) Patients with diabetes were not included in this series. RESULTS: CMO was identified in 5.3% (n = 7) of cases, with 2 of these patients responding to topical corticosteroid treatment. The remaining 5 patients underwent intravitreal dexamethasone implant, with 1 patient requiring repeat implant due to CMO recurrence. All presented within 2 months postoperatively. 4 out of 5 eyes treated with intravitreal dexamethasone achieved a Snellen BCVA ≤6/9.5. 1 patient had an uncontrolled rise in intraocular pressure (IOP) despite maximal medical treatment requiring an urgent PreserFlo Ab-Externo MicroShunt. CONCLUSIONS: The use of intravitreal sustained-release dexamethasone implant in the management of post EK CMO refractory to topical therapy is effective and safe in most cases, but patients should be monitored and treated promptly for any secondary IOP response.

Sutureless Tectonic Mini-Descemet's Stripping Automated Endothelial Keratoplasty ("mini-DSAEK") for the management of corneal perforations.

PURPOSE: To report the outcomes of a new technique, pull-through sutureless 'mini-DSAEK', to manage corneal perforations secondary to different aetiologies including trauma, neurotrophic ulcer following penetrating keratoplasty (PK), herpes simplex keratitis and microbial keratitis. METHODS: In this retrospective case series, we report the clinical outcomes of five cases of sutureless tectonic mini-DSAEK performed in patients presenting with large corneal perforations to Southend University Hospital between November 2019 and October 2020. One corneal perforation was sufficiently peripheral for the tectonic mini-DSAEK graft to be successfully positioned outside of the central visual axis. Four corneal perforations were central or paracentral for which the tectonic grafts involved the visual axis. RESULTS: Anterior chambers remained deep and formed with no evidence of leak in all subsequent follow ups in all patients representing 100% tectonic success. All tectonic grafts remained attached except one partially detached graft. One patient underwent uneventful phacoemulsification with intraocular lens implant 8 months after the primary intervention with excellent visual outcome. Two patients underwent two-piece mushroom PK and one patient underwent triple procedure (cataract extraction + intraocular lens + PK) for visual rehabilitation 2-6 months after the primary intervention with good visual outcome. CONCLUSION: Sutureless tectonic pull-through mini-DSAEK is a useful technique in the management of corneal perforations, with a number of advantages compared with conventional techniques.

One-year post-operative comparison of visual function and patient satisfaction with trifocal and extended depth of focus intraocular lenses.

PURPOSE: To evaluate visual performance with trifocal and extended depth of focus IOL at 1 year post-operatively. SETTING: BMI Southend Hospital. DESIGN: Cohort study. METHODS: An age-matched cohort of forty subjects bilaterally implanted with the AT LISA 839MP trifocal IOL (20 patients, 40 eyes) and the Tecnis Symfony extended depth of focus IOL (20 patients, 40 eyes) were assessed at 3-6 months and 12-18 months post-operatively. Primary outcome measures were distance (6 m), intermediate (70 cm), near visual acuity (40 cm), and analysis of defocus profiles. Secondary outcomes included contrast sensitivity, Radner reading performance, quality of vision and assessment of halos. RESULTS: Distance visual acuity (VA) and defocus areas were similar (p = 0.07). No significant difference in intermediate VA was noted but the intermediate area of focus was greater in the EDoF (0.31 ± 0.12 LogMAR*m-1) compared to the trifocal (0.22 ± 0.08LogMAR*m-1) (p = 0.02). However, all near metrics were significantly better in the trifocal group. 80% of trifocal subjects were spectacle independent compared to 50% EDoF subjects. Quality of vision questionnaire found no significant differences between groups, however halo scores were greater at 3-6 months in the trifocal group (p < 0.01) but no differences were noted at 12-18 months. CONCLUSIONS: Near vision is significantly better for the trifocal, thus greater levels of spectacle independence. The range of intermediate vision was greater for the EDoF but no difference in intermediate VA. In the early period, differences in contrast sensitivity and halo size/intensity were noted, however, by one-year these measures were not significantly different.

Predicting the Postoperative Addition Power of a Multifocal Intraocular Lens at the Spectacle Plane.

PURPOSE: To establish a simple clinical method of predicting addition power achieved with a multifocal intraocular lens (IOL). METHODS: In this prospective cohort study, 41 patients were bilaterally implanted with the Bi-Flex MY multifocal IOL (Medicontur) with +3.50 diopters (D) near addition power. Monocular defocus curves were plotted for each patient and effective addition power was calculated as the dioptric difference between the distance and near inflection points of the defocus curve. Six biometry formulas (Haigis, Holladay, SRK/T, Hill RBF, Barrett Universal II, and Holladay 2) were used to predict the addition power at the spectacle plane. RESULTS: Mean effective addition power was 2.60 ± 0.29 D, with significant (P < .01) differences between the prediction methods. Significant differences were found between predicted and effective addition when the Holladay, SRK/T, Hill RBF, and Holladay 2 formulas were used. A moderate but significant correlation (r = 0.342, P = .033) was found with the Barrett formula, and this was also the method to show the least proportional bias with Bland-Altman analysis. CONCLUSIONS: The study demonstrates that the effective addition power can be predicted using the proposed simple clinical method derived using the Barrett Universal II formula. The proposed technique may have significant clinical value in screening for patients where ocular biometry may lead to aberrant addition power. [J Refract Surg. 2021;37(5):318-323.].

Visual function and subjective perception of vision after bilateral implantation of monofocal and multifocal IOLs: a randomized controlled trial.

PURPOSE: To examine monocular and binocular visual function and patient-reported outcomes after implantation of multifocal IOLs (mIOLs) or monofocal IOLs, using a rigorous series of clinical assessments. SETTING: BMI Southend Hospital, United Kingdom. DESIGN: Prospective, randomized, double-masked clinical trial. METHODS: One hundred patients were randomized for bilateral implantation of either a Bi-Flex 677MY mIOL or a Bi-Flex 677AB IOL and were assessed at 3 to 6 months (V1) and 12 to 18 months (V2). Primary outcomes included distance, intermediate, and near logarithm of the minimum angle of resolution (logMAR) visual acuities (VAs) and defocus curve profile assessment. Secondary outcomes included reading speed, contrast sensitivity (CS), and the subjective perception of quality of vision. RESULTS: Forty-seven subjects with monofocal IOL and 43 mIOL subjects completed the study. Uncorrected (mIOL: 0.10 ± 0.09 logMAR; IOL: 0.09 ± 0.11 logMAR) and corrected (mIOL: 0.04 ± 0.06 logMAR; IOL: 0.01 ± 0.07 logMAR) distance VAs were comparable (P > .05). Uncorrected near VA (mIOL: 0.23 ± 0.13 logMAR; IOL: 0.55 ± 0.20 logMAR, P < .001) and distance-corrected near VA (mIOL: 0.24 ± 0.13 logMAR; IOL: 0.54 ± 0.17 logMAR, P < .001) were significantly improved with mIOLs. There was no significant difference in distance-corrected intermediate VA (mIOL: 0.38 ± 0.13 logMAR; IOL: 0.39 ± 0.13 logMAR, P = .431). Defocus curves demonstrated an increased range-of-focus among mIOLs (mIOL: 4.14 ± 1.10 diopter [D]; IOL: 2.57 ± 0.77 D). Pelli-Robson CS was different at V1 (P < .001) but similar by V2 (P = .059). Overall satisfaction was high (>90%) in both groups for distance tasks whereas significantly different for near tasks (mIOL, 18.45 ± 16.53 logUnits; IOL, 55.59 ± 22.52 logUnits). CONCLUSIONS: Uncorrected near visual acuity was demonstrably better with mIOLs and there was greater subjective satisfaction with quality of near vision. Halos reported by the mIOL group were significant compared with the IOL group but did not show an adverse effect on overall satisfaction.

Clinical outcomes with a new trifocal intraocular lens.

PURPOSE: To evaluate visual and refractive outcomes, contrast sensitivity, and quality of vision after cataract surgery with the implantation of a new modality of trifocal intraocular lens (IOL). METHODS: This case series comprised 30 patients who had bilateral implantation of the AT.LISA tri 839 MP trifocal IOL after phacoemulsification for either cataract or refractive lens exchange surgery. Uncorrected (UDVA) and corrected monocular distance visual acuity (CDVA) using a logMAR chart, binocular uncorrected (UNVA) and corrected near visual acuity (CNVA) (40 cm and patients' preferred distance) using the Radner Reading Charts, distance-corrected intermediate visual acuity (DCIVA) (70 cm), a binocular defocus curve, contrast sensitivity (CS) with the Pelli-Robson test, and subjective quality of vision by a short questionnaire were evaluated at 1, 3, and 6 months postoperatively. RESULTS: At 6 months, mean values of 0.05 ± 0.07 and -0.02 ± 0.05 logMAR were obtained for monocular UDVA and CDVA, respectively. Mean values of 0.16 ± 0.07, 0.12 ± 0.07, and 0.16 ± 0.07 logRAD were obtained for binocular UNVA, CNVA, and DCIVA, respectively. Significant changes were only detected in monocular CDVA (p<0.01) and UDVA that improved between 3 and 6 months postoperatively (p = 0.01). A visual acuity level of 0.2 logRAD could be seen in binocular defocus curves between +1.00 and -3.00 D. At 6 months, mean photopic and mesopic CS were 1.52 ± 0.11 and 1.54 ± 0.11. Regarding the questionnaire, almost all patients were satisfied with their distance, intermediate, and near vision. Difficulties associated with photic phenomena decreased significantly over time. CONCLUSIONS: The AT.LISA trifocal IOL provides excellent uncorrected distance, intermediate, and near visual outcomes.