- Email: [email protected]
Optimal near and distance stereoacuity after binocular implantation of extended range of vision intraocular lenses
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ARTICLE
Optimal near and distance stereoacuity after binocular implantation of extended range of vision intraocular lenses Jeewan S. Titiyal, MD, Manpreet Kaur, MD, Neha Bharti, BSc, Deepali Singhal, MD, Rohit Saxena, MD, Namrata Sharma, MD
Purpose: To evaluate stereopsis and visual quality after bilateral implantation of extended range of vision intraocular lenses (ERV IOLs). Setting: R.P. Centre for Ophthalmic Sciences, AIIMS, New Delhi, India.
Design: Prospective interventional study. Methods: Patients underwent phacoemulsification with bilateral implantation of ERV IOLs. The primary outcome measures were stereopsis (distance and near Randot) and visual quality (raytracing aberrometry). The secondary outcome measures were visual acuity and patient satisfaction. Follow-up was performed on day 1 and at 1, 3, 6, and 12 months postoperatively. Results: The study comprised 50 patients (100 eyes). The mean age of the patients was 58.9 years G 8.9 (SD). At 1 year, the mean distance stereopsis was 103.6 G 49.1 seconds of arc (arcsec) and
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hacoemulsification is increasingly becoming akin to refractive surgical procedures with patients demanding optimal visual quality in addition to precise visual acuity for all distances. A wide armamentarium of premium intraocular lenses (IOLs) are available to cater to the increasing patient expectations, and multifocal IOLs have been developed to provide spectacle independence for both distance as well as near visual acuity. However, the present multifocal IOLs are associated with significant dysphotic symptoms including glare and halos.1–3 The visual quality and contrast sensitivity are suboptimal, especially in dim light conditions. The extended range of vision (ERV) IOLs provide an elongated depth of focus and have been observed to provide good visual acuity across all distances after phacoemulsification, with minimal dysphotic symptoms and
near stereopsis was 21.1 G 2.3 arcsec. Perfect near stereopsis of 20 arcsec was present in 80% of cases, and 82% had good distance stereopsis of 100 arcsec or better. Stereopsis correlated well with the patient satisfaction score (P < .001) and average internal modulation transfer function (MTF) (P < .015). The mean Strehl ratio was 0.029 G 0.021, MTF was 0.24 G 0.08, total higher-order aberrations were 0.62 G 0.41 mm, and coma was 0.25 G 0.18 mm. The mean binocular uncorrected decimal visual acuities were 0.98 G 0.07 (distance), 0.82 G 0.09 (intermediate) and 0.64 G 0.08 (near). The mean patient satisfaction score was 9.08 G 1.1, and no case required IOL explantation because of visually disturbing phenomena or patient dissatisfaction.
Conclusion: Excellent stereoacuity was observed after bilateral implantation of ERV IOLs, which correlated well with patient satisfaction and quality of vision.
J Cataract Refract Surg 2019; -:-–- Q 2019 ASCRS and ESCRS
optimal patient satisfaction.4–7 The ERV IOL has an aspheric anterior surface to compensate for corneal spherical aberrations and an achromatic diffractive surface to correct chromatic aberrations. This results in an increase in retinal image quality without affecting the depth of focus.8 Binocularity and depth perception are essential components of visual quality, and with improving technology, our focus should be to not only provide an optimal visual acuity across all ranges of distances but also an optimal visual quality with excellent binocularity. However, to our knowledge, no study has evaluated the stereopsis after bilateral implantation of ERV IOLs, and the postoperative visual quality has not been adequately analyzed. We herein evaluate the stereoacuity and visual quality after bilateral implantation of ERV IOLs.
Submitted: November 6, 2018 | Final revision submitted: December 13, 2018 | Accepted: December 20, 2018 From the Cornea, Cataract & Refractive Surgery Services (Titiyal, Kaur, Bharti, Singhal, Sharma), and the Squint & Neuro-ophthalmology Services (Saxena), Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. Corresponding author: Jeewan S. Titiyal, MD, Cornea, Cataract & Refractive Surgery Services, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India. Email: [email protected]. Q 2019 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/$ - see frontmatter https://doi.org/10.1016/j.jcrs.2018.12.024
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PATIENTS AND METHODS The prospective interventional study was conducted at an apex tertiary care ophthalmic center (R.P. Centre for Ophthalmic Sciences, AIIMS, New Delhi, India). Ethical clearance was obtained from the institutional review board and the study adhered to the tenets of the Declaration of Helsinki. Written informed consent was obtained from all patients. Fifty patients (100 eyes) planned for phacoemulsification had the ERV IOL (TECNIS Symfony, Abbott Medical Optics, Inc.) bilaterally implanted. All patients with immature senile cataract who planned to undergo phacoemulsification were included in the study. The patients who fulfilled the inclusion criteria were consecutively enrolled from a start point (November 2016). Patients with preoperative corneal astigmatism of more than 0.75 diopter (D), any ocular or systemic comorbidities, and/or a history of ocular surgery including phacoemulsification were excluded from the study. The primary outcome measures were distance and near stereopsis and visual quality. The secondary outcome measures were uncorrected near (UNVA), intermediate (UIVA), and distance (UDVA) visual acuities; patient satisfaction score; and the incidence of dysphotic symptoms. A comprehensive preoperative assessment was performed, including visual acuity (Snellen chart for distance, Early Treatment Diabetic Retinopathy Study chart for near and intermediate), anterior segment examination, posterior segment evaluation, and intraocular pressure measurement. The grade of the cataract was assessed based on the Lens Opacities Classification System III (LOCS III).9 Axial length and keratometry were assessed using optical biometry (IOLMaster 500, Carl Zeiss Meditec AG). Ray-tracing aberrometry was performed with iTrace (Tracey Technologies) to assess angle k and the aberration profile. The power for the ERV IOL was calculated using the SRK/T formula,10 and a near emmetropic power (first myopia) was selected erring on the side of slight postoperative myopia. Phacoemulsification was performed in all cases through a 2.2 mm temporal clear corneal incision as per standard technique on an active-fluidics torsional phacoemulsification machine (Centurion Vision System, Alcon laboratories, Inc.). The second eye of each patient was operated within 1 month of the first eye surgery. All cases were performed by the same surgeon (J.S.T.), who is experienced in phacoemulsification. Any intraoperative complications were recorded. Postoperatively, all patients received topical antibiotics and steroids for 1 month. Topical cycloplegics were administered twice daily for the first postoperative week, followed by once daily for the second week as per the standard postoperative regimen followed at the R.P. Centre for Ophthalmic Sciences. All patients underwent a comprehensive anterior segment evaluation and fundus assessment in the postoperative period.
Stereopsis The stereopsis was assessed with Polaroid-vectograph tests (Polaroid Corp.). Each patient was asked to wear polarizing spectacles before conducting the test. The near stereoacuity was assessed by the Randot Graded Circle Test (Stereo Optical Company, Inc.) at a 33 cm distance, which helps to assess stereopsis ranging from 400 to 20 seconds of arc (arcsec). The distance stereoacuity was assessed using the Distance Randot Stereotest (Stereo Optical Company, Inc.) at a distance of 3 m, which helps to assess stereopsis ranging from 400 to 60 arcsec. The Randot stereotest is a sensitive measurement of binocular sensory status, and it has low variability with high reliability.11 The stereoacuity was noted in arcsec, and a value of 100 arcsec or better was considered as good stereoacuity.12,13 Volume - Issue - - 2019
Visual Quality Visual quality was assessed using the iTrace ray-tracing aberrometer. The examination was performed on a 5.0 mm dilated pupil. The modulation transfer function (MTF), Strehl ratio, and higher-order aberrations (HOAs) were assessed. The MTF curves display the contrast transferred at different spatial frequencies and Strehl ratio is indicative of the point spread function (PSF) of the ocular system.14 Patient Satisfaction A subjective questionnaire (modified National Eye Institute Refractive Error Quality of Life Instrument 42) was administered to all patients to assess the visual disturbances, quality of vision during various activities of daily living, spectacle independence for various distances, and the overall patient satisfaction.5,15 The visual disturbances assessed included glare, night vision problems (starbursts), halos, distortion of near vision, and distortion of distance vision, which were graded as none, mild, moderate, or severe. Difficulties in activities of daily living such as watching television, cellphone use, reading, playing sports, night driving, computer use, and seeing the time on a clock were graded as none, mild, moderate, or severe. The patients were asked about spectacle use after surgery for near, intermediate, and distance, and the response was graded as none (0%), occasionally (25% of time), 50% of time, or 100% of time. The patient satisfaction was assessed on a scale of 1 to 10, with a score of 1 representing “not at all satisfied” and a score of 10 indicating “extremely satisfied.” Visual Acuity The UNVA, UIVA, UDVA, and corrected near, intermediate, and distance visual acuities were assessed at all follow-up visits. The distance vision was assessed at 6 m, intermediate vision was assessed at 66 cm, and the near vision was assessed at 40 cm. Both monocular and binocular visual acuities were assessed. Follow-up was performed at 1 day and 1, 3, 6, and 12 months postoperatively. Statistical Analysis Statistical analysis was done using SPSS Statistics software (version 11.0, SPSS, Inc.). Normally distributed continuous variables were expressed as means G SD and were compared using an independent-samples t test. Non-normally distributed continuous variables were compared using the Mann-Whitney U test. Nominal data were compared using a Chi-square test or a Fisher exact test, as appropriate. Correlation between continuous variables was assessed using a Pearson correlation test. A P value less than 0.05 was considered statistically significant.
RESULTS The study comprised 100 eyes of 50 patients (mean age 59.7 G 8.6 years; range 45 to 78 years). There were 29 women and 21 men. All the patients had immature senile nuclear sclerosis grade II through grade IV (LOCS III). Stereopsis
At 1 year postoperatively, the mean uncorrected distance stereopsis of the cases was 103.6 G 49.1 arcsec (range 60 to 200 arcsec). Fine stereopsis of 60 arcsec was achieved by 18 (36%) of 50 patients and 41 (82%) of 50 patients had good stereopsis of 100 arcsec or better. Nine patients had moderate stereopsis of 200 arcsec and no patient had distance stereopsis less than 200 arcsec. The mean uncorrected near stereopsis was 21.1 G 2.3 arcsec (range 20 to 30 arcsec). Forty (80%) of 50 patients
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achieved perfect near stereopsis of 20 arcsec, and all patients had a stereopsis of 30 arcsec or better. The mean corrected distance stereopsis was 100.8 G 47.46 arcsec (range 60 to 200 arcsec) and the corrected near stereopsis was 20.60 G 1.64 arcsec (range 20 to 25 arcsec). There was a strong correlation between distance and near stereoacuity (Pearson correlation coefficient: 0.344, P Z .015). A significant correlation was observed between the distance stereopsis and patient satisfaction score (Pearson correlation coefficient: 0.713, P !.001) as well as between the near stereopsis and patient satisfaction score (Pearson correlation coefficient: 0.473, P Z .001), with better stereopsis associated with greater patient satisfaction. A significant inverse correlation was also observed between distance stereopsis and average internal MTF, signifying better stereopsis associated with higher MTF values (Pearson correlation coefficient: 0.343, P Z .015). No significant correlation was observed between distance stereopsis and visual acuity (near, intermediate, and distance), Strehl ratio, or HOAs. There was no significant correlation between near stereopsis and visual acuity (near, intermediate, and distance), MTF, Strehl ratio, or HOAs. Visual Quality
Table 1 shows the mean Strehl ratio, MTF, and HOAs as assessed by the ray-tracing aberrometer at 1 year postoperatively. The total mean Strehl ratio was 0.029 G 0.021. The MTF was assessed at 5, 10, and 15 cycles per degree in addition to average MTF. The total average MTF was 0.24 G 0.08 and the mean total HOAs were 0.62 G 0.41 mm. Visual Acuity
Table 2 shows the mean decimal and logarithm of the minimum angle of resolution uncorrected visual acuities at 1 month and 1 year postoperatively. There was no significant difference in visual acuities at 1 month or 1 year for any distance (P O .05). At 1 year postoperatively, a binocular UDVA of 20/20 or better was achieved by 48 (96%) of 50 patients, and all patients had a UDVA of 20/32 or better. A UIVA of 20/25 or better was achieved by 34 (68%) of 50 patients, and 20/29 or better was achieved by 48 patients (96%). All patients had a UIVA of 20/36 or better. A UNVA of N6 (equivalent to 20/40) or better was achieved by 50 (100%) patients. There was no significant difference between the visual acuities at 1 month and 1 year postoperatively (P O .05). The manifest refraction spherical equivalent was within G0.5 D for all patients. Patient Satisfaction
In the immediate postoperative period, mild-to-moderate glare was observed in 10 (20%) of 50 cases, and only 1 case (2%) had severe glare. Distorted night vision (starbursts) was observed in 5 cases (10%). Mild-to-moderate halos were reported by 15 (30%) of the 50 patients. A distortion
Table 1. PSF, MTF, and HOAs after bilateral implantation of extended range of vision intraocular lenses. Visual Quality Parameter PSF Strehl ratio internal Strehl ratio total MTF Internal (5 cpd) Internal (10 cpd) Internal (15 cpd) Internal average Total (5 cpd) Total (10 cpd) Total (15 cpd) Total average HOAs (mm) RMS internal RMS total HOAs internal HOAs total Coma internal Coma total Trefoil internal Trefoil total SA internal SA total Secondary astigmatism internal Secondary astigmatism total
Mean ± SD 0.029 G 0.015 0.029 G 0.021 0.47 G 0.16 0.17 G 0.08 0.10 G 0.04 0.24 G 0.07 0.43 G 0.20 0.20 G 0.13 0.12 G 0.08 0.24 G 0.08 0.84 G 0.65 0.90 G 0.54 0.64 G 0.43 0.62 G 0.41 0.26 G 0.21 0.25 G 0.18 0.27 G 0.27 0.35 G 0.27 0.21 G 0.15 0.10 G 0.12 0.14 G 0.15 0.13 G 0.13
cpd Z cycles per degree; HOAs Z higher-order aberrations; MTF Z modulation transfer function; PSF Z point spread function; RMS Z root mean square; SA Z spherical aberration
of vision was reported by 12 patients (24%) for near and by 10 patients (20%) for distance. At 1 year, 41 (82%) of the 50 patients did not experience any glare after the bilateral ERV IOL implantation. Mild glare persisted in 8 (16%) cases at the end of 1 year and 1 patient (2%) had moderate glare. Mild night vision disturbances were reported by 4 (8%) of the 50 patients. Fourteen (28%) patients reported halos, all of which were
Table 2. Postoperative UDVA, UIVA, and UNVA after bilateral implantation of extended range of vision intraocular lenses. Mean ± SD Visual Acuity UDVA 1 Mo 1Y UIVA 1 Mo 1Y UNVA 1 Mo 1Y
LogMAR Units
Snellen Decimal Units
0.02 G 0.07 0.01 G 0.04
0.96 G 0.12 0.98 G 0.07
0.10 G 0.09 0.09 G 0.06
0.81 G 0.15 0.82 G 0.09
0.20 G 0.08 0.19 G 0.05
0.64 G 0.11 0.64 G 0.08
LogMAR Z logarithm of the minimum angle of resolution; UDVA Z uncorrected distance visual acuity; UIVA Z uncorrected intermediate visual acuity; UNVA Z uncorrected near visual acuity Volume - Issue - - 2019
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characterized as mild. Three (6%) of the 50 patients experienced distortion of near and distance vision, which was mild to moderate in intensity. Forty-four (88%) of the 50 patients engaged in night driving and did not experience any postoperative difficulties, and 6 (12%) patients reported mild difficulty while driving. The ease of performing lifestyle activities was assessed, and no patient experienced any problems in performing computer work, seeing the time on a clock, or using a cellphone. Nearly all (49 [98%]) of the 50 patients reported no visual disturbances while watching television or performing outdoor activities and 1 patient (2%) experienced mild difficulties. Difficulties while reading were reported by 4 patients (8%). Spectacle independence for distance vision was achieved by 48 (96%) of the 50 patients, whereas 2 patients (4%) required only occasional spectacle use. Spectacle independence for intermediate vision was achieved by 47 (94%) of the 50 patients, whereas 2 patients (4%) required occasional spectacle use and 1 patient (2%) required continuous spectacle use. Spectacle independence for near vision was achieved by 31 (62%) of the 50 patients, with 15 patients (30%) requiring occasional spectacles and 4 patients (8%) requiring continuous spectacle use. The mean patient satisfaction score was 9.08 G 1.1 (range 5 to 10). No patient required an explant of the ERV IOL because of visually disturbing phenomena or dissatisfaction with visual quality. Complications
No patient developed intraoperative complications such as posterior capsular rupture, vitreous loss, or nucleus drop. Sutures were not required to help in sealing the wound toward the end of surgery in any case. The ERV IOL was wellcentered in all cases with a 360-degree coverage of the IOL optic by the edges of the capsulorhexis. Postoperatively, no case developed excessive inflammation, secondary glaucoma, cystoid macular edema, or retinal detachment. Posterior capsular opacification was not observed in any case up to 1 year of follow-up. DISCUSSION The ERV IOLs are a recent innovation in the field of premium IOLs with a unique echelette design that increases the depth of focus and provides spectacle independence for all range of distances. It also includes a proprietary achromatic technology that enhances contrast and decreases chromatic aberrations.4,16 We analyzed the stereoacuity and visual quality after bilateral implantation of ERV IOLs. In our study, all patients had a near stereoacuity of 30 arcsec or better and 80% had a perfect near stereopsis of 20 arcsec. The near stereoacuity after ERV IOLs was better compared with previous studies,12,17 which reported near stereopsis after bilateral multifocal or monofocal IOL implantation. A good distance stereoacuity of 100 arcsec or less was achieved by 82% of the patients, although fine distance stereopsis of 60 arcsec was achieved by only 36% of the patients. Previous studies18–20 have reported a worsening of stereoscopic threshold with age and in Volume - Issue - - 2019
pseudophakic patients. The normative values in an older age group have not been adequately described for stereopsis, and the threshold of stereoacuity might vary in patients undergoing cataract surgery. The stereopsis correlated well with patient satisfaction and MTF, emphasizing the significance of a normal binocular interaction in assessing the quality of vision to ensure optimal patient satisfaction. Normal binocular interaction is an essential component of vision, more so in the present era wherein 3-dimension is increasingly being integrated in the day to day life in the form of movies, graphics, and 3-dimension printers.21 The outcome measures evaluating IOL performance typically focus on monocular visual acuities rather than binocular interaction. To our knowledge, distance stereopsis has not been evaluated in pseudophakic patients, and this is the first study to evaluate both distance and near stereoacuity after bilateral implantation of multifocal ERV IOLs. Good visual quality was observed as assessed by the raytracing aberrometer. To our knowledge, no specific cutoff values have been established in the literature to determine good visual quality on the basis of aberrometry analysis, and there is an intersystem variability with a difference on measured values on various aberrometry systems; however, our results largely corroborated with previous studies.5,7,22 MTF is a measure of contrast and the Strehl ratio is a measure of the intensity of the image brightness, with an MTF and Strehl ratio of 1 signifying a perfect optical system.23 A contrast of 16.6% is required for a 20/20 vision and 5% contrast is required for a vision of 20/32.A The average MTF as well as the MTF at lower spatial frequencies of 5 and 10 cycles per degree were greater than 16.6% in our cases. Villegas et al.24 analyzed 60 eyes of young patients with normal to excellent visual acuity, and they observed coma and trefoil variations between 0.0 mm and 0.5 mm and spherical aberrations ranging from 0.45 to C0.45 mm.24 We considered 0.5 mm as the upper limit for coma, trefoil, and spherical aberrations, and all our cases had HOAs less than 0.5 mm. The aspheric design of the ERV IOL compensated for the positive spherical aberrations of the cornea, and the mean total postoperative spherical aberrations were 0.10 G 0.12 mm. At 1 year postoperatively, severe dysphotic phenomena were not experienced by any patient, and this also corroborated with the visual quality assessment on ray-tracing aberrometry. Optimal patient satisfaction was observed, and no patient required additional surgical intervention. The distance and intermediate visual acuities were satisfactory with complete spectacle independence achieved by more than 90% of cases. Although all cases had UNVA of N6 or better, complete spectacle independence could be achieved in only 62% of the cases. We did not target for micromonovision in our study. Previous studies have reported significantly improved near vision and better spectacle independence when a micromonovision of 0.5 D to 0.75 D is targeted.4,25 However, the effect of the targeted anisometropia in micromonovision on stereopsis and visual quality has not been evaluated. We did not evaluate preoperative stereoacuity in our cases.
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To conclude, the ERV IOLs mark a quantum leap in the field of premium IOLs with excellent visual acuity along all range of distances. We observed good binocular interaction with ERV IOLs that correlated well with patient satisfaction and the quality of vision. This points toward the importance of routinely assessing binocular interaction with all IOLs, especially multifocal IOLs. Future studies comparing the visual quality and stereoacuity between different types of IOLs should be performed.
WHAT WAS KNOWN Extended range of vision intraocular lenses (ERV IOLs) provide excellent near, intermediate, and distance visual acuities. The ERV IOL is associated with optimal patient satisfaction and minimal dysphotic symptoms.
WHAT THIS PAPER ADDS Binocular implantation of ERV IOLs provided excellent near and distance stereoacuity that correlated well with patient satisfaction scores and quality of vision. Good visual quality was observed objectively by ray-tracing aberrometry along with an absence of severe dysphotic phenomena and good patient satisfaction.
REFERENCES
mez Fain ~a P, Espan ~a Albelda A, Comas Serrano M, 1. Martínez Palmer A, Go Nahra Saad D, Castilla Cespedes M. Visual function with bilateral implantation of monofocal and multifocal intraocular lenses: a prospective, randomized, controlled clinical trial. J Refract Surg 2008; 24:257–264 2. Knorz MC. Multifocal intraocular lenses: overview of their capabilities, limitations, and clinical benefits. J Refract Surg 2008; 24:215–217 €ring G, Dick HB, Krummenauer F, Weissmantel U, Kro €ncke W. Subjec3. Ha tive photic phenomena with refractive multifocal and monofocal intraocular lenses. Results of a multicenter questionnaire. J Cataract Refract Surg 2001; 27:245–249 4. Cochener B, Concerto Study Group. Clinical outcomes of a new extended range of vision intraocular lens: International Multicenter Concerto Study. J Cataract Refract Surg 2016; 42:1268–1275 5. Pedrotti E, Bruni E, Bonacci E, Badalamenti R, Mastropasqua R, Marchini G. Comparative analysis of the clinical outcomes with a monofocal and an extended range of vision intraocular lens. J Refract Surg 2016; 32:436–442 6. Weeber HA, Meijer ST, Piers PA. Extending the range of vision using diffractive intraocular lens technology. J Cataract Refract Surg 2015; 41:2746– 2754 7. Pedrotti E, Carones F, Aiello F, Mastropasqua R, Bruni E, Bonacci E, Talli P, Nucci C, Mariotti C, Marchini G. Comparative analysis of visual outcomes with 4 intraocular lenses: monofocal, multifocal, and extended range of vision. J Cataract Refract Surg 2018; 44:156–167 8. Weeber HA, Piers PA. Theoretical performance of intraocular lenses correcting both spherical and chromatic aberration. J Refract Surg 2012; 28:48–52 9. Chylack LT, Wolfe JK, Singer DM, Leske MC, Bullimore MA, Bailey IL, Friend J, McCarthy D, Wu SY. The Lens Opacities Classification System III. The Longitudinal Study of Cataract Study Group. Arch Ophthalmol 1993; 111:831–836
10. Retzlaff JA, Sanders DR, Kraff MC. Development of the SRK/T intraocular lens implant power calculation formula. J Cataract Refract Surg 1990; 16:333–340; erratum, 528 11. Wang J, Hatt SR, O’Connor AR, Drover JR, Adams R, Birch EE, Holmes JM. Final version of the Distance Randot Stereotest: normative data, reliability, and validity. J AAPOS 2010; 14:142–146 12. Hayashi K, Hayashi H. Stereopsis in bilaterally pseudophakic patients. J Cataract Refract Surg 2004; 30:1466–1470 13. Katsumi O, Miyajima H, Ogawa T, Hirose T. Aniseikonia and stereoacuity in pseudophakic patients. Unilateral and bilateral cases. Ophthalmology 1992; 99:1270–1277 14. Ligabue EA, Giordano C. Assessing visual quality with the point spread function using the NIDEK OPD-Scan II. J Refract Surg 2009; 25:S104– S109 15. Hays RD, Mangione CM, Ellwein L, Lindblad AS, Spritzer KL, McDonnell PJ. Psychometric properties of the National Eye Institute-Refractive Error Quality of Life instrument. Ophthalmology 2003; 110:2292–2301 16. Yoo YS, Whang WJ, Byun YS, Piao JJ, Kim DY, Joo CK, Yoon G. Throughfocus optical bench performance of extended depth-of-focus and bifocal intraocular lenses compared to a monofocal lens. J Refract Surg 2018; 34:236–243 zaro S, Cervin ~o A, Monte s17. Ferrer-Blasco T, Madrid-Costa D, García-La R. Stereopsis in bilaterally multifocal pseudophakic patients. Graefes Mico Arch Clin Exp Ophthalmol 2011; 249:245–251 18. Lightholder PA, Phillips LJ. Evaluation of the binocularity of 147 unilateral and bilateral pseudophakic patients. Am J Optom Physiol Opt 1979; 56:451–459 19. Garnham L, Sloper JJ. Effect of age on adult stereoacuity as measured by different types of stereotest. Br J Ophthalmol 2006; 90:91–95 20. Brown B, Yap MK, Fan WC. Decrease in stereoacuity in the seventh decade of life. Ophthalmic Physiol Opt 1993; 13:138–142 21. O’Connor AR, Birch EE, Anderson S, Draper H. FSOS Research Group. The functional significance of stereopsis. Invest Ophthalmol Vis Sci 2010; 51:2019–2023 22. Liang CL, Juo SH, Chang CJ. Comparison of higher-order wavefront aberrations with 3 aberrometers. J Cataract Refract Surg 2005; 31:2153– 2156 23. Tuan KM, Chernyak D, Feldman ST. Predicting patients’ night vision complaints with wavefront technology. Am J Ophthalmol 2006; 141:1–6 n E, Artal P. Optical quality of the eye in subjects with 24. Villegas EA, Alco normal and excellent visual acuity. Invest Ophthalmol Vis Sci 2008; 49:4688–4696 25. Hogarty DT, Russell DJ, Ward BM, Dewhurst N, Burt P. Comparing visual acuity, range of vision and spectacle independence in the extended range of vision and monofocal intraocular lens. Clin Exp Ophthalmol 2018; 46:854–860 OTHER CITED MATERIAL A. Schwiegerling J. “Connecting MTF Measurements of Multifocal IOLs to Clinical Measures of Visual Acuity,” presented at the annual meeting of the Association for Research in Vision and Ophthalmology, Fort Lauderdale, Florida, USA, April, 2009
Disclosures: None of the authors has a financial or proprietary interest in any material or method mentioned.
First author: Jeewan S. Titiyal, MD Cornea, Cataract & Refractive Surgery Services, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
Volume - Issue - - 2019
ARTICLE
Optimal near and distance stereoacuity after binocular implantation of extended range of vision intraocular lenses Jeewan S. Titiyal, MD, Manpreet Kaur, MD, Neha Bharti, BSc, Deepali Singhal, MD, Rohit Saxena, MD, Namrata Sharma, MD
Purpose: To evaluate stereopsis and visual quality after bilateral implantation of extended range of vision intraocular lenses (ERV IOLs). Setting: R.P. Centre for Ophthalmic Sciences, AIIMS, New Delhi, India.
Design: Prospective interventional study. Methods: Patients underwent phacoemulsification with bilateral implantation of ERV IOLs. The primary outcome measures were stereopsis (distance and near Randot) and visual quality (raytracing aberrometry). The secondary outcome measures were visual acuity and patient satisfaction. Follow-up was performed on day 1 and at 1, 3, 6, and 12 months postoperatively. Results: The study comprised 50 patients (100 eyes). The mean age of the patients was 58.9 years G 8.9 (SD). At 1 year, the mean distance stereopsis was 103.6 G 49.1 seconds of arc (arcsec) and
P
hacoemulsification is increasingly becoming akin to refractive surgical procedures with patients demanding optimal visual quality in addition to precise visual acuity for all distances. A wide armamentarium of premium intraocular lenses (IOLs) are available to cater to the increasing patient expectations, and multifocal IOLs have been developed to provide spectacle independence for both distance as well as near visual acuity. However, the present multifocal IOLs are associated with significant dysphotic symptoms including glare and halos.1–3 The visual quality and contrast sensitivity are suboptimal, especially in dim light conditions. The extended range of vision (ERV) IOLs provide an elongated depth of focus and have been observed to provide good visual acuity across all distances after phacoemulsification, with minimal dysphotic symptoms and
near stereopsis was 21.1 G 2.3 arcsec. Perfect near stereopsis of 20 arcsec was present in 80% of cases, and 82% had good distance stereopsis of 100 arcsec or better. Stereopsis correlated well with the patient satisfaction score (P < .001) and average internal modulation transfer function (MTF) (P < .015). The mean Strehl ratio was 0.029 G 0.021, MTF was 0.24 G 0.08, total higher-order aberrations were 0.62 G 0.41 mm, and coma was 0.25 G 0.18 mm. The mean binocular uncorrected decimal visual acuities were 0.98 G 0.07 (distance), 0.82 G 0.09 (intermediate) and 0.64 G 0.08 (near). The mean patient satisfaction score was 9.08 G 1.1, and no case required IOL explantation because of visually disturbing phenomena or patient dissatisfaction.
Conclusion: Excellent stereoacuity was observed after bilateral implantation of ERV IOLs, which correlated well with patient satisfaction and quality of vision.
J Cataract Refract Surg 2019; -:-–- Q 2019 ASCRS and ESCRS
optimal patient satisfaction.4–7 The ERV IOL has an aspheric anterior surface to compensate for corneal spherical aberrations and an achromatic diffractive surface to correct chromatic aberrations. This results in an increase in retinal image quality without affecting the depth of focus.8 Binocularity and depth perception are essential components of visual quality, and with improving technology, our focus should be to not only provide an optimal visual acuity across all ranges of distances but also an optimal visual quality with excellent binocularity. However, to our knowledge, no study has evaluated the stereopsis after bilateral implantation of ERV IOLs, and the postoperative visual quality has not been adequately analyzed. We herein evaluate the stereoacuity and visual quality after bilateral implantation of ERV IOLs.
Submitted: November 6, 2018 | Final revision submitted: December 13, 2018 | Accepted: December 20, 2018 From the Cornea, Cataract & Refractive Surgery Services (Titiyal, Kaur, Bharti, Singhal, Sharma), and the Squint & Neuro-ophthalmology Services (Saxena), Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. Corresponding author: Jeewan S. Titiyal, MD, Cornea, Cataract & Refractive Surgery Services, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India. Email: [email protected]. Q 2019 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/$ - see frontmatter https://doi.org/10.1016/j.jcrs.2018.12.024
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PATIENTS AND METHODS The prospective interventional study was conducted at an apex tertiary care ophthalmic center (R.P. Centre for Ophthalmic Sciences, AIIMS, New Delhi, India). Ethical clearance was obtained from the institutional review board and the study adhered to the tenets of the Declaration of Helsinki. Written informed consent was obtained from all patients. Fifty patients (100 eyes) planned for phacoemulsification had the ERV IOL (TECNIS Symfony, Abbott Medical Optics, Inc.) bilaterally implanted. All patients with immature senile cataract who planned to undergo phacoemulsification were included in the study. The patients who fulfilled the inclusion criteria were consecutively enrolled from a start point (November 2016). Patients with preoperative corneal astigmatism of more than 0.75 diopter (D), any ocular or systemic comorbidities, and/or a history of ocular surgery including phacoemulsification were excluded from the study. The primary outcome measures were distance and near stereopsis and visual quality. The secondary outcome measures were uncorrected near (UNVA), intermediate (UIVA), and distance (UDVA) visual acuities; patient satisfaction score; and the incidence of dysphotic symptoms. A comprehensive preoperative assessment was performed, including visual acuity (Snellen chart for distance, Early Treatment Diabetic Retinopathy Study chart for near and intermediate), anterior segment examination, posterior segment evaluation, and intraocular pressure measurement. The grade of the cataract was assessed based on the Lens Opacities Classification System III (LOCS III).9 Axial length and keratometry were assessed using optical biometry (IOLMaster 500, Carl Zeiss Meditec AG). Ray-tracing aberrometry was performed with iTrace (Tracey Technologies) to assess angle k and the aberration profile. The power for the ERV IOL was calculated using the SRK/T formula,10 and a near emmetropic power (first myopia) was selected erring on the side of slight postoperative myopia. Phacoemulsification was performed in all cases through a 2.2 mm temporal clear corneal incision as per standard technique on an active-fluidics torsional phacoemulsification machine (Centurion Vision System, Alcon laboratories, Inc.). The second eye of each patient was operated within 1 month of the first eye surgery. All cases were performed by the same surgeon (J.S.T.), who is experienced in phacoemulsification. Any intraoperative complications were recorded. Postoperatively, all patients received topical antibiotics and steroids for 1 month. Topical cycloplegics were administered twice daily for the first postoperative week, followed by once daily for the second week as per the standard postoperative regimen followed at the R.P. Centre for Ophthalmic Sciences. All patients underwent a comprehensive anterior segment evaluation and fundus assessment in the postoperative period.
Stereopsis The stereopsis was assessed with Polaroid-vectograph tests (Polaroid Corp.). Each patient was asked to wear polarizing spectacles before conducting the test. The near stereoacuity was assessed by the Randot Graded Circle Test (Stereo Optical Company, Inc.) at a 33 cm distance, which helps to assess stereopsis ranging from 400 to 20 seconds of arc (arcsec). The distance stereoacuity was assessed using the Distance Randot Stereotest (Stereo Optical Company, Inc.) at a distance of 3 m, which helps to assess stereopsis ranging from 400 to 60 arcsec. The Randot stereotest is a sensitive measurement of binocular sensory status, and it has low variability with high reliability.11 The stereoacuity was noted in arcsec, and a value of 100 arcsec or better was considered as good stereoacuity.12,13 Volume - Issue - - 2019
Visual Quality Visual quality was assessed using the iTrace ray-tracing aberrometer. The examination was performed on a 5.0 mm dilated pupil. The modulation transfer function (MTF), Strehl ratio, and higher-order aberrations (HOAs) were assessed. The MTF curves display the contrast transferred at different spatial frequencies and Strehl ratio is indicative of the point spread function (PSF) of the ocular system.14 Patient Satisfaction A subjective questionnaire (modified National Eye Institute Refractive Error Quality of Life Instrument 42) was administered to all patients to assess the visual disturbances, quality of vision during various activities of daily living, spectacle independence for various distances, and the overall patient satisfaction.5,15 The visual disturbances assessed included glare, night vision problems (starbursts), halos, distortion of near vision, and distortion of distance vision, which were graded as none, mild, moderate, or severe. Difficulties in activities of daily living such as watching television, cellphone use, reading, playing sports, night driving, computer use, and seeing the time on a clock were graded as none, mild, moderate, or severe. The patients were asked about spectacle use after surgery for near, intermediate, and distance, and the response was graded as none (0%), occasionally (25% of time), 50% of time, or 100% of time. The patient satisfaction was assessed on a scale of 1 to 10, with a score of 1 representing “not at all satisfied” and a score of 10 indicating “extremely satisfied.” Visual Acuity The UNVA, UIVA, UDVA, and corrected near, intermediate, and distance visual acuities were assessed at all follow-up visits. The distance vision was assessed at 6 m, intermediate vision was assessed at 66 cm, and the near vision was assessed at 40 cm. Both monocular and binocular visual acuities were assessed. Follow-up was performed at 1 day and 1, 3, 6, and 12 months postoperatively. Statistical Analysis Statistical analysis was done using SPSS Statistics software (version 11.0, SPSS, Inc.). Normally distributed continuous variables were expressed as means G SD and were compared using an independent-samples t test. Non-normally distributed continuous variables were compared using the Mann-Whitney U test. Nominal data were compared using a Chi-square test or a Fisher exact test, as appropriate. Correlation between continuous variables was assessed using a Pearson correlation test. A P value less than 0.05 was considered statistically significant.
RESULTS The study comprised 100 eyes of 50 patients (mean age 59.7 G 8.6 years; range 45 to 78 years). There were 29 women and 21 men. All the patients had immature senile nuclear sclerosis grade II through grade IV (LOCS III). Stereopsis
At 1 year postoperatively, the mean uncorrected distance stereopsis of the cases was 103.6 G 49.1 arcsec (range 60 to 200 arcsec). Fine stereopsis of 60 arcsec was achieved by 18 (36%) of 50 patients and 41 (82%) of 50 patients had good stereopsis of 100 arcsec or better. Nine patients had moderate stereopsis of 200 arcsec and no patient had distance stereopsis less than 200 arcsec. The mean uncorrected near stereopsis was 21.1 G 2.3 arcsec (range 20 to 30 arcsec). Forty (80%) of 50 patients
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STEREOACUITY WITH ERV IOLS
achieved perfect near stereopsis of 20 arcsec, and all patients had a stereopsis of 30 arcsec or better. The mean corrected distance stereopsis was 100.8 G 47.46 arcsec (range 60 to 200 arcsec) and the corrected near stereopsis was 20.60 G 1.64 arcsec (range 20 to 25 arcsec). There was a strong correlation between distance and near stereoacuity (Pearson correlation coefficient: 0.344, P Z .015). A significant correlation was observed between the distance stereopsis and patient satisfaction score (Pearson correlation coefficient: 0.713, P !.001) as well as between the near stereopsis and patient satisfaction score (Pearson correlation coefficient: 0.473, P Z .001), with better stereopsis associated with greater patient satisfaction. A significant inverse correlation was also observed between distance stereopsis and average internal MTF, signifying better stereopsis associated with higher MTF values (Pearson correlation coefficient: 0.343, P Z .015). No significant correlation was observed between distance stereopsis and visual acuity (near, intermediate, and distance), Strehl ratio, or HOAs. There was no significant correlation between near stereopsis and visual acuity (near, intermediate, and distance), MTF, Strehl ratio, or HOAs. Visual Quality
Table 1 shows the mean Strehl ratio, MTF, and HOAs as assessed by the ray-tracing aberrometer at 1 year postoperatively. The total mean Strehl ratio was 0.029 G 0.021. The MTF was assessed at 5, 10, and 15 cycles per degree in addition to average MTF. The total average MTF was 0.24 G 0.08 and the mean total HOAs were 0.62 G 0.41 mm. Visual Acuity
Table 2 shows the mean decimal and logarithm of the minimum angle of resolution uncorrected visual acuities at 1 month and 1 year postoperatively. There was no significant difference in visual acuities at 1 month or 1 year for any distance (P O .05). At 1 year postoperatively, a binocular UDVA of 20/20 or better was achieved by 48 (96%) of 50 patients, and all patients had a UDVA of 20/32 or better. A UIVA of 20/25 or better was achieved by 34 (68%) of 50 patients, and 20/29 or better was achieved by 48 patients (96%). All patients had a UIVA of 20/36 or better. A UNVA of N6 (equivalent to 20/40) or better was achieved by 50 (100%) patients. There was no significant difference between the visual acuities at 1 month and 1 year postoperatively (P O .05). The manifest refraction spherical equivalent was within G0.5 D for all patients. Patient Satisfaction
In the immediate postoperative period, mild-to-moderate glare was observed in 10 (20%) of 50 cases, and only 1 case (2%) had severe glare. Distorted night vision (starbursts) was observed in 5 cases (10%). Mild-to-moderate halos were reported by 15 (30%) of the 50 patients. A distortion
Table 1. PSF, MTF, and HOAs after bilateral implantation of extended range of vision intraocular lenses. Visual Quality Parameter PSF Strehl ratio internal Strehl ratio total MTF Internal (5 cpd) Internal (10 cpd) Internal (15 cpd) Internal average Total (5 cpd) Total (10 cpd) Total (15 cpd) Total average HOAs (mm) RMS internal RMS total HOAs internal HOAs total Coma internal Coma total Trefoil internal Trefoil total SA internal SA total Secondary astigmatism internal Secondary astigmatism total
Mean ± SD 0.029 G 0.015 0.029 G 0.021 0.47 G 0.16 0.17 G 0.08 0.10 G 0.04 0.24 G 0.07 0.43 G 0.20 0.20 G 0.13 0.12 G 0.08 0.24 G 0.08 0.84 G 0.65 0.90 G 0.54 0.64 G 0.43 0.62 G 0.41 0.26 G 0.21 0.25 G 0.18 0.27 G 0.27 0.35 G 0.27 0.21 G 0.15 0.10 G 0.12 0.14 G 0.15 0.13 G 0.13
cpd Z cycles per degree; HOAs Z higher-order aberrations; MTF Z modulation transfer function; PSF Z point spread function; RMS Z root mean square; SA Z spherical aberration
of vision was reported by 12 patients (24%) for near and by 10 patients (20%) for distance. At 1 year, 41 (82%) of the 50 patients did not experience any glare after the bilateral ERV IOL implantation. Mild glare persisted in 8 (16%) cases at the end of 1 year and 1 patient (2%) had moderate glare. Mild night vision disturbances were reported by 4 (8%) of the 50 patients. Fourteen (28%) patients reported halos, all of which were
Table 2. Postoperative UDVA, UIVA, and UNVA after bilateral implantation of extended range of vision intraocular lenses. Mean ± SD Visual Acuity UDVA 1 Mo 1Y UIVA 1 Mo 1Y UNVA 1 Mo 1Y
LogMAR Units
Snellen Decimal Units
0.02 G 0.07 0.01 G 0.04
0.96 G 0.12 0.98 G 0.07
0.10 G 0.09 0.09 G 0.06
0.81 G 0.15 0.82 G 0.09
0.20 G 0.08 0.19 G 0.05
0.64 G 0.11 0.64 G 0.08
LogMAR Z logarithm of the minimum angle of resolution; UDVA Z uncorrected distance visual acuity; UIVA Z uncorrected intermediate visual acuity; UNVA Z uncorrected near visual acuity Volume - Issue - - 2019
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STEREOACUITY WITH ERV IOLS
characterized as mild. Three (6%) of the 50 patients experienced distortion of near and distance vision, which was mild to moderate in intensity. Forty-four (88%) of the 50 patients engaged in night driving and did not experience any postoperative difficulties, and 6 (12%) patients reported mild difficulty while driving. The ease of performing lifestyle activities was assessed, and no patient experienced any problems in performing computer work, seeing the time on a clock, or using a cellphone. Nearly all (49 [98%]) of the 50 patients reported no visual disturbances while watching television or performing outdoor activities and 1 patient (2%) experienced mild difficulties. Difficulties while reading were reported by 4 patients (8%). Spectacle independence for distance vision was achieved by 48 (96%) of the 50 patients, whereas 2 patients (4%) required only occasional spectacle use. Spectacle independence for intermediate vision was achieved by 47 (94%) of the 50 patients, whereas 2 patients (4%) required occasional spectacle use and 1 patient (2%) required continuous spectacle use. Spectacle independence for near vision was achieved by 31 (62%) of the 50 patients, with 15 patients (30%) requiring occasional spectacles and 4 patients (8%) requiring continuous spectacle use. The mean patient satisfaction score was 9.08 G 1.1 (range 5 to 10). No patient required an explant of the ERV IOL because of visually disturbing phenomena or dissatisfaction with visual quality. Complications
No patient developed intraoperative complications such as posterior capsular rupture, vitreous loss, or nucleus drop. Sutures were not required to help in sealing the wound toward the end of surgery in any case. The ERV IOL was wellcentered in all cases with a 360-degree coverage of the IOL optic by the edges of the capsulorhexis. Postoperatively, no case developed excessive inflammation, secondary glaucoma, cystoid macular edema, or retinal detachment. Posterior capsular opacification was not observed in any case up to 1 year of follow-up. DISCUSSION The ERV IOLs are a recent innovation in the field of premium IOLs with a unique echelette design that increases the depth of focus and provides spectacle independence for all range of distances. It also includes a proprietary achromatic technology that enhances contrast and decreases chromatic aberrations.4,16 We analyzed the stereoacuity and visual quality after bilateral implantation of ERV IOLs. In our study, all patients had a near stereoacuity of 30 arcsec or better and 80% had a perfect near stereopsis of 20 arcsec. The near stereoacuity after ERV IOLs was better compared with previous studies,12,17 which reported near stereopsis after bilateral multifocal or monofocal IOL implantation. A good distance stereoacuity of 100 arcsec or less was achieved by 82% of the patients, although fine distance stereopsis of 60 arcsec was achieved by only 36% of the patients. Previous studies18–20 have reported a worsening of stereoscopic threshold with age and in Volume - Issue - - 2019
pseudophakic patients. The normative values in an older age group have not been adequately described for stereopsis, and the threshold of stereoacuity might vary in patients undergoing cataract surgery. The stereopsis correlated well with patient satisfaction and MTF, emphasizing the significance of a normal binocular interaction in assessing the quality of vision to ensure optimal patient satisfaction. Normal binocular interaction is an essential component of vision, more so in the present era wherein 3-dimension is increasingly being integrated in the day to day life in the form of movies, graphics, and 3-dimension printers.21 The outcome measures evaluating IOL performance typically focus on monocular visual acuities rather than binocular interaction. To our knowledge, distance stereopsis has not been evaluated in pseudophakic patients, and this is the first study to evaluate both distance and near stereoacuity after bilateral implantation of multifocal ERV IOLs. Good visual quality was observed as assessed by the raytracing aberrometer. To our knowledge, no specific cutoff values have been established in the literature to determine good visual quality on the basis of aberrometry analysis, and there is an intersystem variability with a difference on measured values on various aberrometry systems; however, our results largely corroborated with previous studies.5,7,22 MTF is a measure of contrast and the Strehl ratio is a measure of the intensity of the image brightness, with an MTF and Strehl ratio of 1 signifying a perfect optical system.23 A contrast of 16.6% is required for a 20/20 vision and 5% contrast is required for a vision of 20/32.A The average MTF as well as the MTF at lower spatial frequencies of 5 and 10 cycles per degree were greater than 16.6% in our cases. Villegas et al.24 analyzed 60 eyes of young patients with normal to excellent visual acuity, and they observed coma and trefoil variations between 0.0 mm and 0.5 mm and spherical aberrations ranging from 0.45 to C0.45 mm.24 We considered 0.5 mm as the upper limit for coma, trefoil, and spherical aberrations, and all our cases had HOAs less than 0.5 mm. The aspheric design of the ERV IOL compensated for the positive spherical aberrations of the cornea, and the mean total postoperative spherical aberrations were 0.10 G 0.12 mm. At 1 year postoperatively, severe dysphotic phenomena were not experienced by any patient, and this also corroborated with the visual quality assessment on ray-tracing aberrometry. Optimal patient satisfaction was observed, and no patient required additional surgical intervention. The distance and intermediate visual acuities were satisfactory with complete spectacle independence achieved by more than 90% of cases. Although all cases had UNVA of N6 or better, complete spectacle independence could be achieved in only 62% of the cases. We did not target for micromonovision in our study. Previous studies have reported significantly improved near vision and better spectacle independence when a micromonovision of 0.5 D to 0.75 D is targeted.4,25 However, the effect of the targeted anisometropia in micromonovision on stereopsis and visual quality has not been evaluated. We did not evaluate preoperative stereoacuity in our cases.
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STEREOACUITY WITH ERV IOLS
To conclude, the ERV IOLs mark a quantum leap in the field of premium IOLs with excellent visual acuity along all range of distances. We observed good binocular interaction with ERV IOLs that correlated well with patient satisfaction and the quality of vision. This points toward the importance of routinely assessing binocular interaction with all IOLs, especially multifocal IOLs. Future studies comparing the visual quality and stereoacuity between different types of IOLs should be performed.
WHAT WAS KNOWN Extended range of vision intraocular lenses (ERV IOLs) provide excellent near, intermediate, and distance visual acuities. The ERV IOL is associated with optimal patient satisfaction and minimal dysphotic symptoms.
WHAT THIS PAPER ADDS Binocular implantation of ERV IOLs provided excellent near and distance stereoacuity that correlated well with patient satisfaction scores and quality of vision. Good visual quality was observed objectively by ray-tracing aberrometry along with an absence of severe dysphotic phenomena and good patient satisfaction.
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10. Retzlaff JA, Sanders DR, Kraff MC. Development of the SRK/T intraocular lens implant power calculation formula. J Cataract Refract Surg 1990; 16:333–340; erratum, 528 11. Wang J, Hatt SR, O’Connor AR, Drover JR, Adams R, Birch EE, Holmes JM. Final version of the Distance Randot Stereotest: normative data, reliability, and validity. J AAPOS 2010; 14:142–146 12. Hayashi K, Hayashi H. Stereopsis in bilaterally pseudophakic patients. J Cataract Refract Surg 2004; 30:1466–1470 13. Katsumi O, Miyajima H, Ogawa T, Hirose T. Aniseikonia and stereoacuity in pseudophakic patients. Unilateral and bilateral cases. Ophthalmology 1992; 99:1270–1277 14. Ligabue EA, Giordano C. Assessing visual quality with the point spread function using the NIDEK OPD-Scan II. J Refract Surg 2009; 25:S104– S109 15. Hays RD, Mangione CM, Ellwein L, Lindblad AS, Spritzer KL, McDonnell PJ. Psychometric properties of the National Eye Institute-Refractive Error Quality of Life instrument. Ophthalmology 2003; 110:2292–2301 16. Yoo YS, Whang WJ, Byun YS, Piao JJ, Kim DY, Joo CK, Yoon G. Throughfocus optical bench performance of extended depth-of-focus and bifocal intraocular lenses compared to a monofocal lens. J Refract Surg 2018; 34:236–243 zaro S, Cervin ~o A, Monte s17. Ferrer-Blasco T, Madrid-Costa D, García-La R. Stereopsis in bilaterally multifocal pseudophakic patients. Graefes Mico Arch Clin Exp Ophthalmol 2011; 249:245–251 18. Lightholder PA, Phillips LJ. Evaluation of the binocularity of 147 unilateral and bilateral pseudophakic patients. Am J Optom Physiol Opt 1979; 56:451–459 19. Garnham L, Sloper JJ. Effect of age on adult stereoacuity as measured by different types of stereotest. Br J Ophthalmol 2006; 90:91–95 20. Brown B, Yap MK, Fan WC. Decrease in stereoacuity in the seventh decade of life. Ophthalmic Physiol Opt 1993; 13:138–142 21. O’Connor AR, Birch EE, Anderson S, Draper H. FSOS Research Group. The functional significance of stereopsis. Invest Ophthalmol Vis Sci 2010; 51:2019–2023 22. Liang CL, Juo SH, Chang CJ. Comparison of higher-order wavefront aberrations with 3 aberrometers. J Cataract Refract Surg 2005; 31:2153– 2156 23. Tuan KM, Chernyak D, Feldman ST. Predicting patients’ night vision complaints with wavefront technology. Am J Ophthalmol 2006; 141:1–6 n E, Artal P. Optical quality of the eye in subjects with 24. Villegas EA, Alco normal and excellent visual acuity. Invest Ophthalmol Vis Sci 2008; 49:4688–4696 25. Hogarty DT, Russell DJ, Ward BM, Dewhurst N, Burt P. Comparing visual acuity, range of vision and spectacle independence in the extended range of vision and monofocal intraocular lens. Clin Exp Ophthalmol 2018; 46:854–860 OTHER CITED MATERIAL A. Schwiegerling J. “Connecting MTF Measurements of Multifocal IOLs to Clinical Measures of Visual Acuity,” presented at the annual meeting of the Association for Research in Vision and Ophthalmology, Fort Lauderdale, Florida, USA, April, 2009
Disclosures: None of the authors has a financial or proprietary interest in any material or method mentioned.
First author: Jeewan S. Titiyal, MD Cornea, Cataract & Refractive Surgery Services, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
Volume - Issue - - 2019