Intraocular lenses for presbyopia correction: past, present, and future

Presbyopia Treatments by Mechanism of Action: A New Classification System Based on a Review of the Literature

Presbyopia, a loss of accommodative ability associated with aging, is a significant cause of vision impairment globally. At the clinical level, it is a frustrating and difficult issue that negatively impacts patients’ quality of life. Less appreciated is the fact that loss of accommodative ability and its current treatments methods may present safety concerns, for example, increasing the risk of falls. Therefore, a more complete understanding of treatment options with respect to how they relate to the natural ability of the eye is needed to improve decision making and to aid clinicians in individualizing treatment options. This article reviews the options for expanding functional through focus—a term coined to describe the ability of the eye to see at all distances with minimal latency—by how they vary the refractive power over time, across the visual field, between eyes, or across a range of distances.

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Visual outcomes of binocular implantation of a new extended depth of focus intraocular lens

Purpose:

To evaluate the visual outcomes of bilateral implantation of a new hydrophobic foldable extended depth of focus (EDOF) IOL.

Methods:

All cases undergoing phacoemulsification with bilateral implantation of Supraphob Infocus IOL between December 2017 and July 2018 at a tertiary eye care center were recruited in this prospective interventional study. The primary outcome measures were uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), and uncorrected near visual acuity (UNVA). Postoperative follow-up was done on day 1, 1 week, 1 month, and 3 months.

Results:

One hundred and four eyes of 52 patients with a mean age of 58.4 ± 9.3 years were included. The mean UDVA improved from 0.84 ± 0.32 logMAR preoperatively to 0.11 ± 0.08 logMAR at 3 months following surgery. At the final follow-up, the binocular UDVA, UIVA, and UNVA was 0.03 ± 0.07, 0.14 ± 0.06, and 0.36 ± 0.05 logMAR, respectively. The mean CS was 1.47 ± 0.06 logCS. The distance and near stereopsis was 90.2 ± 24.8 s of arc (arcsec) and 62.5 ± 19.4 arcsec, respectively. The mean total higher-order aberration (HOA), point spread function, and modulation transfer function were 0.30 ± 0.13, 0.07 ± 0.08, and 0.26 ± 0.07, respectively.

Conclusion:

The Supraphob Infocus EDOF IOL provides good unaided visual acuity for distance, intermediate, and near along with a high quality of vision as assessed by contrast sensitivity, HOAs, and stereoacuity. It may be a potential alternative to the currently available EDOF IOLs in providing good visual acuity at variable distances.

Unilateral Versus Bilateral Refractive Lens Exchange With a Trifocal Intraocular Lens in Emmetropic Presbyopic Patients

PURPOSE

To compare visual outcomes and patient satisfaction between unilateral and bilateral trifocal diffractive intraocular lens (IOL) implantation in emmetropic patients with presbyopia.

DESIGN

Retrospective observational case series.

METHODS

This is a multicenter, multisurgeon study of emmetropic presbyopes who underwent refractive lens exchange (RLE) followed by an implantation of FineVision IOL (PhysIOL). Inclusion criteria were emmetropic eyes, with a sphere between -0.25 and +0.50 diopters (D), cylinder of less than 0.75 D and spherical equivalent (SE) between -0.25 and +0.25 D. In addition, uncorrected distance visual acuity (UDVA) had to be Snellen >0.9 in each eye. A total of 171 eyes of 122 patients were evaluated. This sample was divided into 2 groups depending on whether they have been operated monocularly or binocularly. Visual and refractive performance, patient satisfaction, and spectacle independence were evaluated.

RESULTS

UDVA and corrected distance visual acuity (CDVA) remained almost unchanged after monocular and binocular surgery. Binocular uncorrected intermediate (UIVA) and near visual acuity (UNVA) were better in those operated binocularly (0.3±0.12 vs 0.22±0.06, P < .063, and 0.09±0.08 vs 0.04±0.05, P < .027, respectively). Predictability and efficacy were higher in the binocular group, whereas safety was better in the monocular group. Visual dysphotopsia was worse and spectacle independence for all distances was higher in binocular group.

CONCLUSIONS

Our research shows that RLE with binocular implantation of a trifocal diffractive IOL in presbyopic emmetropic patients is more successful in UNVA than monocular implantation. However, no significant differences were observed in UDVA, UIVA, and patient satisfaction.

Evaluation of the Cataract Surgery 2018 Survey in Terms of Achieving Refractive Cataract Surgery Targets

Objectives

The aim of this study was to show at what rate the technological equipment used in cataract surgery by Turkish ophthalmologists and their knowledge are reflected in practice and how up to date they are.

Materials and Methods

A questionnaire conducted using SurveyMonkey was used to evaluate the answers to 17 questions from 823 members of the Turkish Ophthalmological Association. Results were evaluated in subgroups according to the participants' age, occupational status, institutions, and whether they conducted relevant academic activities, and the data were compared as inadequate, standard, and contemporary approaches according to the determined criteria.

Results

Optical biometry devices were used at rates of 77.7% and 67.3% for intraocular lens (IOL) power calculations and keratometric measurements in preparation for cataract surgery, respectively. For IOL power calculation, third-generation formulas, especially the SRK-T, were used most commonly (46.2%), followed by second-generation formulas (21.9%), and fourth/fifth-generation formulas and multiple evaluations for different axial lengths (31.9%). The most common incision size was 2.8 mm (51.6%), while the percentage of 2.2 mm and shorter incisions considered to be neutral in terms of surgically induced astigmatism was 18.8%. When selecting incision location, approaches to reduce corneal astigmatism were reported by 28.9%, neutral approaches by 26.2%, and insensitive approaches by 44.9%. Additionally, 55.6% of participants never implanted toric IOLs and 50.7% did not use presbyopia-correcting IOLs. The proportion of surgeons who have experience with femtosecond laser-assisted cataract surgery was 10.3% and the rate of intracameral antibiotic injection at the end of the operation was 89.4%.

Conclusion

It was seen that Turkish cataract surgeons were able to use high technology for surgical preparation and surgery at high rates, but this was not reflected in practice at same rate in terms of achieving contemporary standards of refractive cataract surgery.

Corneal Stromal Filler Injection as a Novel Approach to Correct Presbyopia-An Ex Vivo Pilot Study

Purpose

To evaluate the ex vivo feasibility of corneal stromal filler injection to create bifocality to correct presbyopia by flattening the central posterior corneal surface and thus increase refractive power.

Methods

Femtosecond laser-assisted corneal stromal pockets of varying diameters close to the posterior corneal curvature were cut into rabbit eyes ex vivo. Subsequently, hyaluronic acid was injected to flatten the central posterior curvature. Refractive parameters were determined using perioperatively acquired three-dimensional optical coherence tomography (OCT) scans. Using micrometer-resolution OCT, corneal endothelial cell morphology and density were evaluated.

Results

Following filler injection into the corneal stromal pockets, a fair volume-dependent increase of central refractive power up to 4 diopters (dpt) was observed. Unremarkable refractive changes of the peripheral posterior (3 mm, 0.20 ± 0.11 dpt; 2 mm, 0.11 ± 0.10 dpt) and the anterior corneal curvature (3 mm, 0.20 ± 0.34 dpt; 2 mm, 0.33 ± 0.31 dpt) occurred. Only negligible changes in astigmatism were observed. Different sizes of optical zones could be established. Furthermore, no alterations of corneal endothelial morphology or endothelial cell density (2831 ± 356 cells/mm² vs. 2734 ± 292 cells/mm²; P = 0.552) due to the adjacent laser treatment were observed.

Conclusions

The ex vivo investigations proved the principle of injecting a filler material into femtosecond laser-created corneal stromal pockets close to the posterior corneal curvature as an efficacious, individually adjustable, and novel approach to correct presbyopia without ablating corneal tissue.

Translational Relevance

Due to the aging population worldwide, presbyopia is an increasing problem; thus, our study may encourage further exploration to extend the treatment spectrum of clinically used femtosecond laser systems to correct presbyopia.

Refractive surgery beyond 2020

Refractive surgery refers to any procedure that corrects or minimizes refractive errors. Today, refractive surgery has evolved beyond the traditional laser refractive surgery, embodied by the popular laser in situ keratomileusis or 'LASIK'. New keratorefractive techniques such as small incision lenticule extraction (SMILE) avoids corneal flap creation and uses a single laser device, while advances in surface ablation techniques have seen a resurgence in its popularity. Presbyopic treatment options have also expanded to include new ablation profiles, intracorneal implants, and phakic intraocular implants. With the improved safety and efficacy of refractive lens exchange, a wider variety of intraocular lens implants with advanced optics provide more options for refractive correction in carefully selected patients. In this review, we also discuss possible developments in refractive surgery beyond 2020, such as preoperative evaluation of refractive patients using machine learning and artificial intelligence, potential use of stromal lenticules harvested from SMILE for presbyopic treatments, and various advances in intraocular lens implants that may provide a closer to 'physiological correction' of refractive errors.

Relations between patient personality and patients' dissatisfaction after multifocal intraocular lens implantation: clinical study based on the five factor inventory personality evaluation

To assess the level of visual function and the influence of personality traits on patients' (pts) satisfaction with the visual function following the four different MIOL implantation.

METHODS

We evaluated the visual outcomes over a 6 months follow-up period after cataract surgery with bilateral implantation of four different multifocal IOLs. The spectacle independence, photic phenomena, the influence of personality traits on patients' satisfaction with the visual function were assessed.

RESULTS

A total of 170 eyes of 85 pts were included. There was no statistically significant difference in UDVA (F = 1.6 p = 0.177) and CNVA (F = 1.2 p = 0.30) between the groups 6 months after the surgery. The ReSTOR group had a worse CDVA than the M-flex (p = 0.019) and TECNIS (p = 0.005) groups. The ReSTOR and AT.LISAtri groups had a statistically significantly better UNVA than the M-flex (p = 0.020 and p = 0.013) and TECNIS groups (p = 0.001 both). The independence on spectacles for near distance was from 71.8% (in M-flex group) to 100% (in ReSTOR). The answers of the pts with the prevailing neurotic personality type contradicted the answers given by the pts with other prevailing personality types (p < 0.01).

CONCLUSIONS

MIOL implantation helped ensure better postoperative visual acuity, but some pts were unhappy with the postoperative outcomes. It was established that the subjective satisfaction or dissatisfaction of patients after MIOL implantation is related to certain personality traits: pts with neuroticism as the dominant personality trait were least happy with the postoperative outcomes; pts with conscientiousness and agreeableness as dominant personality traits demonstrated the highest satisfaction with the postoperative outcomes.

Vision with different presbyopia corrections simulated with a portable binocular visual simulator

Presbyopes can choose today among different corrections to provide them with functional vision at far and near, and the outcomes and patient satisfaction depend on the selection. In this study, we present a binocular and portable vision simulator, based on temporal multiplexing of two synchronized tunable lenses allowing see-through and programmable visual simulations of presbyopic corrections. Seventeen binocular corrections were tested: 3 Monofocal (Far, Intermediate, Near), 4 Simultaneous Vision (bifocal, trifocal), 2 Monovision (far and near in either eye) and 8 Modified Monovision corrections (Simultaneous vision in one eye, Monofocal in the other eye). Perceived visual quality was assessed through the simulated corrections in 8 cyclopleged subjects who viewed a composite realistic visual scene with high contrast letters and a landscape at far (4 m) and a high contrast text at intermediate (66 cm) and near (33 cm) distances. Perceptual scores were obtained on a scale of 0 to 5 (low to high perceived quality). Perceptual preference was assessed by judging 36 random image pairs (6 repetitions) viewed through 9 binocular presbyopic corrections using two-interval forced choice procedures. The average score, across far and near distances, was the highest for Monovision (4.4±0.3), followed by Modified Monovision (3.4±0.1), Simultaneous Vision (3.0±0.1) and Monofocal corrections (2.9±0.2). However, the mean difference between far and near was lower for Simultaneous Vision and Monovision (0.4±0.1 PS) than Modified Monovision (1.8±0.7) or monofocal corrections (3.3±1.5). A strong significant correlation was found between the perceptual scores and the percentages of energy in focus, for each correction and distance (R = 0.64, p<0.0001). Multivariate ANOVA revealed significant influence of observation distances (p<10-9) and patients (p = 0.01) on Perceptual Score. In conclusion, we have developed a binocular portable vision simulator that can simulate rapidly and non-invasively different combinations of presbyopic corrections. This tool has applications in systematic clinical evaluation of presbyopia corrections.

Unilateral Refractive Lens Exchange with a Multifocal Intraocular Lens in Emmetropic Presbyopic Patients

Purpose: To evaluate the visual outcome and patient satisfaction after a unilateral multifocal IOL implantation in the non-dominant eye of emmetropic patients with presbyopia. Methods: An interventional case series of consecutive patients who underwent unilateral phacoemulsification with femto-laser assisted cataract surgery (FLACS) and refractive lens exchange (RLE), followed by an implantation of a trifocal diffractive IOL (FineVision Micro F), was performed in the non-dominant eyes of emmetropic patients with presbyopia. After 6 months of follow-up, the main outcome measures were uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), and uncorrected near visual acuity (UNVA). Secondary outcomes included spherical equivalent (SE), refraction, contrast sensitivity, patient questionnaire and presence of visual side effects. Results: A total of 26 eyes of 26 patients, with an average age of 53.8 ± 4.1 years, were included in this study. Preoperative mean UDVA was 0.13 ± 0.04 logMAR (Snellen 20/27), UIVA was 0.46 ± 0.12 logMAR (Snellen 20/58), and UNVA was 0.66 ± 0.17 logMAR (Snellen 20/91), in comparison to postoperative mean UDVA of 0.18 ± 0.32 logMAR (Snellen 20/30) (p = 0.32), UIVA of 0.17 ± 0.21 logMAR (Snellen 20/30) (p < 0.005), and UNVA of 0.02 ± 0.10 logMAR (Snellen 20/21) (p < 0.005). Monocular UNVA of 20/25 or better in the operated eye was achieved in 23 (88%) patients. Twenty-four (96%) patients said they would recommend this procedure to family and friends. There were no intraoperative complications and no IOL exchange was required. Conclusions: A unilateral RLE of the non-dominant eye with FLACS and a trifocal diffractive IOL (FineVision Micro F) implantation in emmetropic, presbyopic patients is provides satisfactory distance, intermediate, and near visual outcomes with no complications reported in this preliminary case series.

Comparative Analysis of Double and Trifocal IOL Implantation in Femtosecond Laser-Assisted Cataract Surgery

Purpose: to compare the clinical results of implantations of bi-and trifocal intraocular lenses (IOL) in femtosecond laser-assisted cataract surgery. Patients and methods. The article presents the results of the Acrysof IQ Panoptix trifocal lens implantations in 84 patients (112 eyes) — the main group and Acrysof IQ Restor bifocal IOL implantations in 52 patients (98 eyes) — the control group. All patients underwent femtosecond laser-assisted cataract surgery (FLACS). The following data were evaluated: uncorrected distance visual acuity (UCDVA) , uncorrected near visual acuity (30–45 cm) and at an average distance (50–70 cm) at discharge, after 14 days, 1 and 3 months after the surgery under photopic and mesopic lighting conditions. Postoperative refractometry data; the defocusing curve was performed in patients with a high UCDVA (0.9–1.0) monocularly under photopic conditions using standard optotypes 14 days after surgery; aberrometry indicators. Results. It was shown that both lenses provided high uncorrected distance and near visual acuity in photopic lighting conditions. At the same time, the Acrysof IQ Panoptix lens provided significantly better visual acuity at an intermediate distance and was more resistant to defocusing conditions. Refraction data: after 1 month, emmetropia was observed in 87 % of patients in the main group and in 85 % of control group, after 6 months — 92 and 89 % respectively. There were no significant differences in high order aberrations and total aberrations between patients of the compared groups. Conclusion. The use of the PanOptix trifocal lens made it possible to obtain maximum visual acuity at different distances, regardless of the level of illumination.

Continuous Transitional Focus (CTF): A New Concept in Ophthalmic Surgery

Presbyopia is a condition that affects many as the lens ages, and is a secondary effect of cataract surgery. Multifocal lenses for the treatment of presbyopia have been undergoing cycles of development and improvement over the past two decades. The latest advancements have yielded lenses with a continuous range of optical powers, otherwise known as continuous transitional focus (CTF) lenses. Modern CTF lenses provide a more natural experience for patients while minimizing unwanted optical side effects.

Clinical application of accommodating intraocular lens

The present review describes recent advances in application of accommodating intraocular lenses (AIOLs). Standard monofocal intraocular lenses (MIOLs) only correct distance vision, while AIOLs are designed to allow both good distance vision and near vision, which is achieved through the contraction and relaxation of ciliary muscles by providing transformation of the axial movement or curvature of the lens. Thus, AIOLs may be a better choice for those patients who demand a higher level of visual performance. Since techniques to analyze the performance of AIOLs have not been standardized, and there is a variety of both subjective and objective methods, it is hard to measure the performance of these intraocular lenses. By evaluating advantages and disadvantages of various AIOLs, and introducing techniques for measurement the performance postoperative, this paper can provide some relative information on choosing the type of AIOLs in the clinic.

Visual Results Following Implantation of a Refractive Multifocal Intraocular Lens in One Eye and a Diffractive in the Contralateral Eye

Objectives

To assess the visual outcomes in patients who underwent cataract surgery with multifocal intraocular lens (IOL) implantation using a “mix and match” approach.

Materials and Methods

Twenty patients (40 eyes) were involved in this prospective, nonrandomized study. Refractive multifocal IOLs (ReZoom NXG1) were implanted in patients’ dominant eyes and diffractive multifocal IOLs (Tecnis ZMA00) were implanted in their non-dominant eyes. Monocular and binocular uncorrected distance, intermediate and near visual acuity (logMAR), and contrast sensitivity levels were measured at 1, 3, and 6 months after cataract surgery. Defocus curves, reading speeds, patient satisfaction, spectacle dependence, and halo and glare symptoms were also evaluated at 6 months after the surgery. Postoperative quality of life was assessed with the Turkish version of National Eye Institute Visual Function Questionnaire-25.

Results

The study group comprised 8 females and 12 males with a mean age of 69.45±10.76 years (range, 31-86 years). The uncorrected distance and intermediate visual acuity levels were significantly better in the ReZoom-implanted eyes at postoperative 6 months (p=0.026 and p=0.037, respectively). There was no statistically significant difference in uncorrected near visual acuity (p>0.05). There was no statistically significant difference in contrast sensitivity, reading speed, halos, or glare between the groups (p<0.05). Mild glare/halo was reported by 40% of the subjects. The mean patient satisfaction was 95% and all patients were spectacle independent.

Conclusion

Mixing and matching multifocal IOLs in selected cataract patients provides excellent visual outcome, a high level of patient satisfaction, and spectacle independency.

Fundamentals of Presbyopia: visual processing and binocularity in its transformation

Background

The accommodation has considerable interactions with the pupil response, vergence response and binocularity. The transformation of visual reception processing and the changes of the binocular cooperation during the presbyopia development are still poorly studied. So, the regularities of visual system violation in the presbyopia formation need to be characterized. This study aims to reveal the transformation of visual reception processing and to determine the role of disturbances in binocular interactions in presbyopia formation.

Methods

This study included 60 people with emmetropic refraction, uncorrected distance visual acuity 1.0 or higher (decimal scale), normal color perception, without concomitant ophthalmopathology. The first group consisted of 30 people (from 18 to 27 years old) without presbyopia, the second cohort comprised 30 patients (from 45 to 55 years old) with presbyopia. The eyeball anatomy and optics were evaluated using ultrasound biomicroscopy, aberrometry, and pupillometry. The functional state of the visual system was investigated under monocular and binocular conditions. The registration of the disparate fusional reflex limits was performed by the original technic using a diploptic device which facilitated investigation of the binocular interaction under natural conditions without the accommodation response, but with the different vergence load. The disparate fusional reflex was analyzed using the proximal and distal fusion borders, and the convergence and divergence fusion borders. The calculation of the area of binocularity field was performed in cm².

Results

The presbyopia formation is characterized by a change in an intraocular anatomy, optics, visual processing, and binocularity. The processes of binocular interaction inhibition make a significant contribution to the misalignment of the visual perception. The modification of the proximal, distal and convergence fusion borders was determined. It was revealed that 87% of the presbyopic patients had binocularity shortage, whereas the reduction of binocularity field area in extreme grade was seen in 6% of cases.

Conclusions

The presbyopia formation is accompanied by a significant reorganization of the visual system activity and by the creation of the new visual processing interactions. These data may be useful in presbyopia surgery.

Clinical outcomes of a new diffractive trifocal intraocular lens with Enhanced Depth of Focus (EDOF)

BACKGROUND

To evaluate the clinical outcomes after the implantation of a new trifocal diffractive intraocular lens (IOL) combined with Enhanced depth of focus (EDOF) technology.

METHODS

The study enrolled 80 eyes of 40 patients who underwent cataract surgery with bilateral implantation of a diffractive trifocal IOL (Reviol Tri-ED) designed with a combination of enhanced depth of focus. Mean age was 52.09 ± 11.32 years (range from 45 to 70 years). Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA), corrected intermediate visual acuity (CIVA), uncorrected near visual acuity (UNVA), corrected near visual acuity (CNVA), keratometry (K), and manifest refraction spherical equivalent (MRSE) were evaluated pre- and postoperatively. The contrast sensitivity, defocus curves, and a questionnaire evaluating individual satisfaction were also estimated.

RESULTS

There was a significant improvement in UDVA, CDVA, UNVA, CNVA, CIVA postoperatively. The defocus curve confirmed good visual acuity also in the intermediate distance. The postoperative MRSE was ranged from -0.75 to 0.75 diopters. Contrast sensitivity also significantly improved postoperatively. The patient satisfaction was high.

CONCLUSION

The new trifocal EDOF IOL provides visual improvement for far, intermediate, and near distances with a high level of visual quality and patient satisfaction.

Clinical Evaluation of Functional Vision of +1.5 Diopters near Addition, Aspheric, Rotational Asymmetric Multifocal Intraocular Lens

PURPOSE

To evaluate postoperative outcomes and visual performance in intermediate distance after implantation of a +1.5 diopters (D) addition, aspheric, rotational asymmetric multifocal intraocular lens (MIOL).

METHODS

Patients underwent bilateral cataract surgery with implantation of an aspheric, asymmetric MIOL with +1.5 D near addition. A complete ophthalmological examination was performed preoperatively and 3 months postoperatively. The main outcome measures were monocular and binocular uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA), distance corrected intermediate visual acuity (DCIVA), uncorrected near visual acuity (UNVA) and distance corrected keratometry, and manifest refraction. The Salzburg Reading Desk was used to analyze unilateral and bilateral functional vision with uncorrected and corrected reading acuity, reading distance, reading speed, and the smallest log-scaled print size that could be read effectively at near and intermediate distances.

RESULTS

The study comprised 60 eyes of 30 patients (mean age, 68.30 ± 9.26 years; range, 34 to 80 years). There was significant improvement in UDVA and CDVA. Mean UIVA was 0.01 ± 0.09 logarithm of the minimum angle of resolution (logMAR) and mean DCIVA was -0.02 ± 0.11 logMAR. In Salzburg Reading Desk analysis for UIVA, the mean subjective intermediate distance was 67.58 ± 8.59 cm with mean UIVA of -0.02 ± 0.09 logMAR and mean word count of 96.38 ± 28.32 words/min.

CONCLUSIONS

The new aspheric, asymmetric, +1.5 D near addition MIOL offers good results for distance visual function in combination with good performance for intermediate distances and functional results for near distance.

Visual acuity and patient satisfaction at varied distances and lighting conditions after implantation of an aspheric diffractive multifocal one-piece intraocular lens

PURPOSE

The aim of the study is to evaluate the visual acuity and patient satisfaction at varied distances under photopic and mesopic lighting conditions in patients bilaterally implanted with aspheric diffractive multifocal one-piece intraocular lenses.

METHODS

In this retrospective-prospective study, 16 patients with a mean age of 66.2±9.2 years (range: 50-81 years) who had undergone bilateral phacoemulsification surgery with implantation of a Tecnis multifocal one-piece intraocular lens (ZMB00) were evaluated. Monocular and binocular uncorrected and distance-corrected visual acuities were measured at distance (20 ft), intermediate (70-80 cm), and near (35-40 cm) under photopic (85 cd/m(2)) and mesopic (3 cd/m(2)) lighting conditions and were compared using the paired t-test. All patients also completed a subjective questionnaire.

RESULTS

At a mean follow-up of 9.5±3.9 months, distance, near, and intermediate visual acuity improved significantly from preoperative acuity. Under photopic and mesopic conditions, 93.8% and 62.5% of patients, respectively, had binocular uncorrected intermediate visual acuity of 20/40 or better, and 62.5% and 31.3% of patients had binocular uncorrected near visual acuity of 20/20 or better. All patients were satisfied with their overall vision without using glasses and/or contact lenses when compared with before surgery. A total of 87.5% of patients reported no glare and 68.8% of patients reported no halos around lights at night.

CONCLUSION

Tecnis multifocal one-piece intraocular lenses provide good distance, intermediate, and near visual acuity under photopic as well as mesopic lighting conditions. High levels of spectacle independence with low levels of photic phenomenon were achieved, resulting in excellent patient satisfaction.

Testing vision with angular and radial multifocal designs using Adaptive Optics

Multifocal vision corrections are increasingly used solutions for presbyopia. In the current study we have evaluated, optically and psychophysically, the quality provided by multizone radial and angular segmented phase designs. Optical and relative visual quality were evaluated using 8 subjects, testing 6 phase designs. Optical quality was evaluated by means of Visual Strehl-based-metrics (VS). The relative visual quality across designs was obtained through a psychophysical paradigm in which images viewed through 210 pairs of phase patterns were perceptually judged. A custom-developed Adaptive Optics (AO) system, including a Hartmann-Shack sensor and an electromagnetic deformable mirror, to measure and correct the eye's aberrations, and a phase-only reflective Spatial Light Modulator, to simulate the phase designs, was developed for this study. The multizone segmented phase designs had 2-4 zones of progressive power (0 to +3D) in either radial or angular distributions. The response of an "ideal observer" purely responding on optical grounds to the same psychophysical test performed on subjects was calculated from the VS curves, and compared with the relative visual quality results. Optical and psychophysical pattern-comparison tests showed that while 2-zone segmented designs (angular & radial) provided better performance for far and near vision, 3- and 4-zone segmented angular designs performed better for intermediate vision. AO-correction of natural aberrations of the subjects modified the response for the different subjects but general trends remained. The differences in perceived quality across the different multifocal patterns are, in a large extent, explained by optical factors. AO is an excellent tool to simulate multifocal refractions before they are manufactured or delivered to the patient, and to assess the effects of the native optics to their performance.

Bifocal refractive corneal inlay implantation to improve near vision in emmetropic presbyopic patients

PURPOSE

To evaluate the safety and effectiveness of the Flexivue Microlens corneal inlay for the improvement of near vision in emmetropic presbyopic patients.

SETTING

Ophthalmology Department, Misericordia e Dolce Hospital, Prato, Italy.

DESIGN

Prospective interventional case series.

METHODS

Corneal inlay implantation was performed in nondominant eyes using a 150 kHz femtosecond laser (iFS). Refraction, uncorrected (UNVA) and corrected (CNVA) near visual acuities, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, slitlamp evaluation, wavefront aberrometry, photopic and mesopic contrast sensitivity, anterior segment optical coherence tomography, endothelial cell density, and central corneal thickness measurements were assessed preoperatively and at each postoperative visit.

RESULTS

The study evaluated 81 eyes. In 26 eyes, the mean preoperative UNVA and UDVA were 0.76 logMAR and 0.00 logMAR, respectively, compared with 0.10 logMAR and 0.15 logMAR, respectively, 36 months postoperatively. Sixteen (62%) of 26 treated eyes lost more than 1 line of UDVA, and 5 (19%) lost more than 2 lines of UDVA. Two eyes (8%) lost more than 1 line of CDVA at 36 months. The mean binocular UDVA was 0.00 logMAR preoperatively and 0.02 logMAR at 36 months. The mean spherical aberration increased after surgery. Statistically significant differences in the mean mesopic and photopic contrast sensitivities at higher spatial frequencies were found between treated eyes and nontreated eyes. Explantation was performed in 6 treated eyes because of halos, glare, and a reduced UDVA.

CONCLUSION

The corneal inlay might be a safe and effective method of improving UNVA in emmetropic presbyopic patients.

FINANCIAL DISCLOSURE

Dr. Fantozzi is a member of the Presbia medical advisory board. No other author has a financial or proprietary interest in any material or method mentioned.

The Effect of Age, Accommodation, and Refractive Error on the Adult Human Eye

PURPOSE

To quantify changes in ocular dimensions associated with age, refractive error, and accommodative response, in vivo, in 30- to 50-year-old human subjects.

METHODS

The right eyes of 91 adults were examined using ultrasonography, phakometry, keratometry, pachymetry, interferometry, anterior segment optical coherence tomography, and high-resolution magnetic resonance imaging. Accommodation was measured subjectively with a push-up test and objectively using open-field autorefraction. Regression analyses were used to assess differences in ocular parameters with age, refractive error, and accommodation.

RESULTS

With age, crystalline lens thickness increased (0.03 mm/yr), anterior lens curvature steepened (0.11 mm/yr), anterior chamber depth decreased (0.02 mm/yr), and lens equivalent refractive index decreased (0.001/yr) (all p < 0.01). With increasing myopia, there were significant increases in axial length (0.37 mm/D), vitreous chamber depth (0.34 mm/D), vitreous chamber height (0.09 mm/D), and ciliary muscle ring diameter (0.10 mm/D) (all p < 0.05). Increasing myopia was also associated with steepening of both the cornea (0.16 mm/D) and anterior lens surface (0.011 mm/D) (both p < 0.04). With accommodation, the ciliary muscle ring diameter decreased (0.08 mm/D) and the muscle thinned posteriorly (0.008 mm/D), allowing the lens to shorten equatorially (0.07 mm/D) and thicken axially (0.06 mm/D) (all p < 0.03).

CONCLUSIONS

Refractive error is significantly correlated with not only the axial dimensions but also the anterior equatorial dimension of the adult eye. Further testing and development of accommodating intraocular lenses should account for differences in patients' preoperative refractive error.

Anterior haptic flexing and in-the-bag subluxation of an accommodating intraocular lens due to excessive capsular bag contraction

We describe the case of a patient who had cataract surgery with implantation of the hydrophilic acrylic Tetraflex accommodating intraocular lens (IOL), with subsequent development of capsulorhexis phimosis and in-the-bag IOL subluxation. Contraction of the capsular bag secondary to fibrosis resulted in significant anterior flexing of the lens haptic component. Explantation of the IOL-capsular bag complex was required 7 years after implantation. Histopathologic analysis demonstrated multiple areas of thick anterior subcapsular fibrosis. Pseudoexfoliative material was present throughout the surface of the lens capsule. Intraocular lenses manufactured from hydrophilic acrylic material are highly flexible and may be more susceptible to capsule contraction, even in the absence of predisposing ocular and systemic conditions. This case highlights the importance of developing guidelines regarding patient screening and selection for the appropriate use of accommodating and other highly flexible IOLs.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Binocular function to increase visual outcome in patients implanted with a diffractive trifocal intraocular lens

Background

To evaluate binocular visual outcome for near, intermediate and distance compared to monocular visual outcome at the same distances in patients implanted with a diffractive trifocal intraocular lens (IOL).

Methods

The study comprised of 100 eyes of 50 patients that underwent bilateral refractive lens exchange or cataract surgery with implantation of a multifocal diffractive IOL (AT LISA tri 839MP, Carl Zeiss Meditech, Germany). A complete ophthalmological examination was performed preoperatively and 3 month postoperatively. The main outcome measures were monocular and binocular uncorrected distance (UDVA), corrected distance (CDVA), uncorrected intermediate (UIVA), and uncorrected near visual acuities (UNVA), keratometry, and manifest refraction.

Results

The mean age was 59.28 years ± 9.6 [SD] (range 44–79 years), repectively. There was significant improvement in UDVA, UIVA, UNVA and CDVA. Comparing the monocular results to the binocular results there was a statistical significant better binocular outcome in all distances (UDVA p = 0.036; UIVA p < 0.0001; UNVA p = 0.001). The postoperative manifest refraction was in 86 % of patients within ± 0.50 [D].

Conclusions

The trifocal IOL improved near, intermediate, and distance vision compared to preoperatively. In addition a statistical significant increase for binocular visual function in all distances could be found.

Trial registration

German Clinical Trials Register (DRKS) DRKS00007837

Visual outcomes and patient satisfaction with a rotational asymmetric refractive intraocular lens for emmetropic presbyopia

PURPOSE

To evaluate the efficacy, safety, predictability, and patient satisfaction after refractive lens exchange with a zonal refractive intraocular lens (IOL) with an inferior reading addition in emmetropic patients.

SETTING

Optical Express, London, United Kingdom.

DESIGN

Retrospective case series.

METHODS

Emmetropic presbyopic patients who had implantation of a Lentis Mplus LS-313 MF30 IOL were evaluated. Inclusion criteria were sphere between -0.50 diopter (D) and +1.00 D with no more than 0.75 D of refractive cylinder and an uncorrected distance visual acuity (UDVA) of 6/6 or better in each eye. The main outcome measures were monocular and binocular UDVA, uncorrected near visual acuity (UNVA), corrected distance visual acuity (CDVA), and patient satisfaction. Three months data are presented.

RESULTS

Four hundred forty eyes of 220 patients were evaluated. The mean monocular UDVA changed from -0.04 logMAR ± 0.06 (SD) preoperatively to -0.04 ± 0.11 logMAR postoperatively (P = .39). The mean CDVA was -0.10 ± 0.05 logMAR preoperatively and -0.09 ± 0.06 logMAR postoperatively (P = .06). At 3 months, 99.7% of eyes were within ±1.00 D of emmetropia. The mean UNVA was 0.13 ± 0.14 logMAR monocularly and 0.10 ± 0.12 logMAR binocularly. On the patient satisfaction questionnaire, 91.9% of patients said the refractive procedure improved their lives and 93.5% were willing to recommend it to friends and family. Three patients requested IOL exchange because of severe night-vision phenomena or unsatisfactory quality of vision.

CONCLUSION

Refractive lens exchange with this zonal refractive IOL was safe in emmetropic presbyopic patients.

FINANCIAL DISCLOSURE

Dr. Schallhorn is a consultant to Abbott Medical Optics. No other author has a financial or proprietary interest in any material or method mentioned.

Translating ocular biomechanics into clinical practice: current state and future prospects

Biomechanics is the study of the relationship between forces and function in living organisms and is thought to play a critical role in a significant number of ophthalmic disorders. This is not surprising, as the eye is a pressure vessel that requires a delicate balance of forces to maintain its homeostasis. Over the past few decades, basic science research in ophthalmology mostly confirmed that ocular biomechanics could explain in part the mechanisms involved in almost all major ophthalmic disorders such as optic nerve head neuropathies, angle closure, ametropia, presbyopia, cataract, corneal pathologies, retinal detachment and macular degeneration. Translational biomechanics in ophthalmology, however, is still in its infancy. It is believed that its use could make significant advances in diagnosis and treatment. Several translational biomechanics strategies are already emerging, such as corneal stiffening for the treatment of keratoconus, and more are likely to follow. This review aims to cultivate the idea that biomechanics plays a major role in ophthalmology and that the clinical translation, lead by collaborative teams of clinicians and biomedical engineers, will benefit our patients. Specifically, recent advances and future prospects in corneal, iris, trabecular meshwork, crystalline lens, scleral and lamina cribrosa biomechanics are discussed.

Multifocal intraocular lenses: relative indications and contraindications for implantation

This article presents an extensive overview of best clinical practice pertaining to selection and use of multifocal intraocular lenses (IOLs) currently available in the United States. Relevant preoperative diagnostic evaluations, patient selection criteria, counseling, and managing expectations are reviewed, as well as how to approach patients with underlying ocular intricacies or challenges and best practices for intraoperative challenges during planned implantation of a multifocal IOL. Managing the unhappy multifocal IOL patient if implantation has been performed is also addressed.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Clinical outcomes after cataract surgery with implantation of the Tecnis ZMB00 multifocal intraocular lens

Background

The aim of this study was to evaluate visual performance, contrast sensitivity, and patient satisfaction in patients undergoing cataract surgery with bilateral implantation of the Tecnis ZMB00 diffractive multifocal IOL (intraocular lens).

Material/Methods

This was a prospective study of 40 eyes of 20 patients with an age range from 48 to 67 years and undergoing cataract surgery with implantation of the diffractive 1-piece IOL Tecnis ZMB00 (Abbott Medical Optics) in 1 eye and 3 weeks later in the other eye. The following parameters were evaluated at 3 and 6 months after the operation: binocular uncorrected distance, intermediate and near visual acuity (UDVA, UIVA, UNVA), uncorrected binocular photopic and mesopic distance and photopic near contrast sensitivity (CSV-1000), subjective symptoms, and patient satisfaction (VF-14).

Results

No significant change was observed in logMAR UDVA between 3 and 6 months postoperatively (−0.11±0.14 vs. −0.10±0.13, p>0.05). In contrast, UNVA (0.06±0.12 vs. −0.02±0.12, p=0.004) and UIVA (0.12±0.15 vs. 0.07±0.11, p=0.005) in this period improved significantly. At 3 and 6 months after surgery, 85% of patients no longer needed to wear corrective lenses. Contrast sensitivity under different conditions was within normal age-matched limits, with significant improvements for some spatial frequencies at 3 and 6 months after surgery (p<0.04). Mean overall patient satisfaction was 9.39±1.06 and 9.19±1.20 (scale from 1 to 10, with 10 being the best score) at 3 and 6 months, respectively. Low level of halo perception was reported in 75% of patients.

Conclusions

The Tecnis ZMB00 IOL provides an effective restoration of the distance, intermediate, and near visual function, allowing patients to be totally free of need to wear corrective lenses and providing high levels of patient satisfaction.

Long-term visual outcomes after Crystalens(®) HD intraocular lens implantation

Purpose

Our purpose was to evaluate the long-term visual outcomes after bilateral implantation of Crystalens^® HD (Bausch and Lomb, Inc.) accommodative intraocular lenses.

Methods

In this study, 25 patients (50 eyes) who underwent cataract surgery and bilateral Crystalens HD accommodative intraocular lens implantation were included. The Crystalens HD lens was implanted in the bag in both eyes, without any intra- or postoperative complications. The visual parameters measured before and after surgery were: uncorrected distance visual acuity, corrected distance visual acuity (CDVA) (using the Early Diabetic Retinopathy Study [EDTRS] logMAR charts), uncorrected intermediate visual acuity, and uncorrected near visual acuity using a Birkhäuser reading chart, at a distance of 66 cm and 33 cm for intermediate and near vision, respectively, directly illuminated by a lamp of 60 watts. After surgery, the patients were evaluated at 1, 3, 6, 12, 24, and 36 months.

Results

The mean age was 68.70±7.1 (range: 54 to 83) years. The mean follow-up was 42.72±0.49 (range: 42.33 to 43.27) months. The uncorrected distance visual acuity improved from 0.56±0.41 (range: 0 to 2) preoperatively to 0.19±0.13 (range: 0 to 0.38) (logMAR scale) at the last follow-up visit, and the CDVA improved from 0.17±0.18 (range: 0 to 0.7) preoperatively to 0.05±0.05 (range: −0.02 to 0.22) at the last follow-up visit. No eyes lost lines of CDVA during the follow-up period, while 54% of patients gained one or more lines of CDVA. The uncorrected intermediate and near visual acuity was J2 or better in 71% and 69% of our patients, respectively.

Conclusion

Crystalens HD implantation seems to provide an improvement in visual acuity for far, intermediate, and near distances.

Presbyopia-correcting intraocular lenses and corneal refractive procedures: a review for retinal surgeons

PURPOSE

To review the specific challenges and pitfalls that vitreoretinal surgeons may face when operating on eyes with presbyopia-correcting intraocular lenses or previous corneal refractive surgery. In addition, this review aims to familiarize vitreoretinal surgeons with specifications of currently available Food and Drug Administration-approved presbyopia-correcting intraocular lenses.

METHODS

Review of current literature performed with PubMed for search terms "presbyopia," "correction," "IOL," "vitreoretinal," "challenges," and "surgical" both singly and in combination as well as closely related terms.

RESULTS AND CONCLUSION

Specific intraoperative issues with presbyopia-correcting intraocular lenses that may be encountered include peripheral visualization, condensation, lens material issues particularly with silicone oil, decentration, Z-syndrome, and foveal image displacement. Every patient undergoing retinal surgery should also be asked about previous laser-assisted in situ keratomileusis/photorefractive keratectomy because those eyes require special attention to surface hydration and care to avoid epithelial removal if possible. Intracorneal ring segments and corneal inlays can cause effects similar to those of a small pupil. However, these can be managed with thorough preoperative evaluation and various intraoperative maneuvers. In addition, retinal physicians should be aware that macular disorders, such as age-related macular degeneration, may be exacerbated by potential loss of contrast sensitivity.

Vignetting and field of view with the KAMRA corneal inlay

PURPOSE

To evaluate the effect of the KAMRA corneal inlay on the retinal image brightness in the peripheral visual field.

METHODS

A KAMRA inlay was "implanted" into a theoretical eye model in a corneal depth of 200 microns. Corneal radius was varied to a steep, normal, and flat (7.37, 7.77, and 8.17 mm) version keeping the proportion of anterior to posterior radius constant. Pupil size was varied from 2.0 to 5.0 mm. Image brightness was determined for field angles from -70° to 70° with and without KAMRA and proportion of light attenuation was recorded.

RESULTS

In our parameter space, the attenuation in brightness ranges in between 0 and 60%. The attenuation in brightness is not affected by corneal shape. For large field angles where the incident ray bundle is passing through the peripheral cornea, brightness is not affected. For combinations of small pupil sizes (2.0 and 2.5 mm) and field angles of 20-40°, up to 60% of light may be blocked with the KAMRA.

CONCLUSION

For combinations of pupil sizes and field angles, the attenuation of image brightness reaches levels up to 60%. Our theoretical findings have to be clinically validated with detailed investigation of this vignetting effect.

Multiple zone multifocal phase designs

New multifocal phase designs aiming at expanding depth of focus in the presbyopic eye are presented. The designs consist of multiple radial or angular zones of different powers or of combined low- and high-order aberrations. Multifocal performance was evaluated in terms of the dioptric range for which the optical quality is above an appropriate threshold, as well as in terms of the area under the through-focus optical quality curves. For varying optical power designs optimal through-focus performance was found for a maximum of three to four zones. Furthermore adding more zones decreased the optical performance of the solution. Angular zone designs provided better multifocal performance (1.95 times on average) than radial zone designs with identical number of zones and the same power range. The optimal design (angular design with three zones) surpassed by 33% the multifocal performance of a bifocal angular zone design and by 32% a standard multifocal phase plate with induced spherical aberration only. By using combinations of low- and high-order aberrations the through-focus range can be extended further by another 0.5 D beyond that of the best design of varying optical power. These designs can be implemented in adaptive optics systems for testing their visual performance in subjects and converted into multifocal contact lenses, intraocular lenses, or presbyopic corneal laser ablation profiles.

[Clinical results after implantation of a new segmental refractive multifocal intraocular lens]

BACKGROUND

The aim of the study was a clinical evaluation of an intraocular lens (IOL) with a segmental multifocal optic design and near addition of + 3.0 D as part of a CE approval study.

PATIENTS AND METHODS

In a multicenter study the LENTIS Mplus LS-312 MF IOL (Oculentis) was implanted in 134 eyes of 79 patients with a mean age of 68 ± 12 years. The multifocality is achieved by implementation of a distance part and a segmented near sector. Three months after surgery, uncorrected and best corrected distance visual acuity (UCDVA and BCDVA, respectively), near visual acuity (UCNVA and BCNVA, respectively), contrast vision and patient satisfaction (questionnaire) were evaluated.

RESULTS

The IOLs were implanted uneventfully either unilaterally or bilaterally and 3 months postoperatively (n = 86 eyes) the following mean visual acuities were obtained (logMAR): UCDVA = 0.05, BCDVA = - 0.01, UCNVA = 0.09 and BCNVA = 0.02. Contrast sensitivity (n = 25 eyes) was within normal limits. Of the 66 questioned patients 10.6% spontaneously reported halos and 3% glare.

CONCLUSION

This new innovative multifocal IOL concept showed very good functional results as well as high patient satisfaction.

Biomechanical eye model and measurement setup for investigating accommodating intraocular lenses

We present a biomechanical eye model to induce pseudophakic accommodative movement for evaluation of the focal shift of accommodative intraocular lenses. Therefore, an accommodative intraocular lens (IOL) was implanted into freshly enucleated porcine eyes. The eyes were glued into a mechanical apparatus to expand the ciliar body effectuating mechanical accommodation. An optical coherence tomographer was used to measure positional and geometrical changes of the IOL for different levels of expansion. The expansion unit allowed stretching of the globe of several millimeters. With the biomechanical eye model we were able to simulate the mechanical functionality of accommodation as well as to measure the lens vault and change in geometry. Accommodative vault could only be measured with an intact vitreous, indicating that the vitreous plays an important role for the functionality of accommodative IOLs.

Age-related eye disease

As with many organs, compromised function of the eye is accompanied with age and has become increasingly prevalent with the aging population. When decreased visual loss becomes significant, patients' ability to perform activities of daily living becomes compromised. This decrease in function is met with morbidity and mortality, as well as a large socioeconomic burden throughout the world. This review summarizes the most common age-related eye diseases, including cataract, glaucoma, diabetic retinopathy, retinal vein occlusion, and age-related macular degeneration. Although our understanding of the genetic and biochemical pathways of these diseases is sill at its primitive stages, we have become able to help our patients improve the quality of life as they age.

Quantification of age-related and per diopter accommodative changes of the lens and ciliary muscle in the emmetropic human eye

PURPOSE

To calculate age-related and per diopter (D) accommodative changes in crystalline lens and ciliary muscle dimensions in vivo in a single cohort of emmetropic human adults ages 30 to 50 years.

METHODS

The right eyes of 26 emmetropic adults were examined using ultrasonography, phakometry, anterior segment optical coherence tomography, and high resolution magnetic resonance imaging. Accommodation was measured both subjectively and objectively.

RESULTS

In agreement with previous research, older age was linearly correlated with a thicker lens, steeper anterior lens curvature, shallower anterior chamber, and lower lens equivalent refractive index (all P < 0.01). Age was not related to ciliary muscle ring diameter (CMRD) or lens equatorial diameter (LED). With accommodation, lens thickness increased (+0.064 mm/D, P < 0.001), LED decreased (-0.075 mm/D, P < 0.001), CMRD decreased (-0.105 mm/D, P < 0.001), and the ciliary muscle thickened anteriorly (+0.013 to +0.026 mm/D, P < 0.001) and thinned posteriorly (-0.011 to -0.015, P < 0.01). The changes per diopter of accommodation in LED, CMRD, and ciliary muscle thickness were not related to subject age.

CONCLUSIONS

The per diopter ciliary muscle contraction is age independent, even as total accommodative amplitude declines. Quantifying normal biometric dimensions of the accommodative structures and changes with age and accommodative effort will further the development of new IOLs designed to harness ciliary muscle forces.

Influence of anterior segment power on the scan path and RNFL thickness using SD-OCT

PURPOSE

Retinal nerve fiber layer (RNFL) thickness measures with spectral domain-optical coherence tomography (SD-OCT) provide important information on the health of the optic nerve. As with most retinal imaging technologies, ocular magnification characteristics of the eye must be considered for accurate analysis. While effects of axial length have been reported, the effects of anterior segment optical power on RNFL thickness measures have not been described fully to our knowledge. The purpose of our study was to determine the influence of the optical power change at the anterior corneal surface, using contact lenses, on the location of the scan path and measurements of RNFL thickness in normal healthy eyes.

METHODS

We recruited 15 normal subjects with less than 6 diopters (D) of ametropia and no ocular pathology. One eye of each subject was selected randomly for scanning. Baseline SD-OCT scans included raster cubes centered on the optic nerve and macula, and a standard 12-degree diameter RNFL scan. Standard 12-degree RNFL scans were repeated with 10 separate contact lenses, (Proclear daily, Omafilcon A/60%) ranging from +8 to -12 D in 2-D steps. The extent of the retinal scan, and RNFL thickness and area measures were quantified using custom MATLAB programs that included ocular biometry measures (IOL Master).

RESULTS

RNFL thickness decreased (0.52 μm/D, r = -0.33, P < 0.01) and the retinal region scanned increased (0.52%/D, r = 0.97, P < 0.01) with increase in contact lens power (-12 to +8). The normalized/percentage rates of change of RNFL thickness (-0.11/mm, r = -0.67, P < 0.01) and image size (0.11/mm, r = 0.96, P < 0.01) were related to axial length. Changes in the retinal region scanned were in agreement with transverse scaling, computed with a three surface schematic eye (R(2) = 0.97, P < 0.01). RNFL area measures, that incorporated the computed transverse scaling, were not related significantly to contact lens power (863 μm(2)/D, r = 0.06, P = 0.47).

CONCLUSIONS

Measurements of RNFL thickness by SD-OCT are dependent on the optics of the eye, including anterior segment power and axial length. The relationships between RNFL thickness measures and optical power are a direct reflection of scan path location with respect to the optic nerve head rim, caused by relative magnification. An incorporation of transverse scaling to RNFL area measures, based on individualized ocular biometry, eliminated the magnification effect.