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Functional visual acuity after neodymium:YAG laser capsulotomy in patients with posterior capsule opacification and good visual acuity preoperatively
ARTICLE
Functional visual acuity after neodymium:YAG laser capsulotomy in patients with posterior capsule opacification and good visual acuity preoperatively Tais Hitomi Wakamatsu, MD, Takefumi Yamaguchi, MD, Kazuno Negishi, MD, Minako Kaido, MD, Yukihiro Matsumoto, MD, Reiko Ishida, MD, Takashi Kojima, MD, Osama Mohamed Aly Ibrahim, MD, Megumi Saiki, CO, Murat Dogru, MD, Kazuo Tsubota, MD
PURPOSE: To evaluate the changes in functional visual acuity before and after neodymium:YAG (Nd:YAG) laser capsulotomy. SETTING: Keio University Hospital, Tokyo, Japan. DESIGN: Case series. METHODS: Eyes that had previous cataract surgery with a clinical diagnosis of central posterior capsule opacity requiring Nd:YAG laser capsulotomy were evaluated. All patients had refractive error and corrected distance visual acuity (CDVA) measurements; slitlamp microscopy examinations, including posterior capsule opacification evaluation; high-contrast visual acuity measured at 5 m using a Landolt chart; 10% low-contrast visual acuity (LCVA); functional visual acuity; wavefront examination; and a Schirmer test without anesthesia. RESULTS: The study enrolled 9 patients (4 women, 5 men; 10 eyes) with a mean age of 57.3 years G 7.0 (SD) (range 47 to 68 years). Although there was no significant difference in CDVA before and after Nd:YAG capsulotomy, there was a significant improvement in the mean functional visual acuity, from 0.18 G 0.11 logMAR (range 0.03 to 0.31 logMAR) to 0.08 G 0.07 logMAR (range 0.04 to 0.18 logMAR) (P<.05). The LCVA improved significantly after Nd:YAG laser capsulotomy (PZ.003). Higher-order aberrations and the root mean square of the 4th-order coefficients decreased significantly after capsulotomy, and these aberrations were significantly correlated with functional visual acuity and LCVA. CONCLUSION: Results indicate that measurement of functional visual acuity is useful in assessing the quality of vision in patients who have Nd:YAG laser capsulotomy after cataract surgery. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2011; 37:258–264 Q 2011 ASCRS and ESCRS
Posterior capsule opacification (PCO) is one of the most common complications of uneventful cataract surgery. It occurs when lens epithelial cells proliferate and migrate across the posterior capsule.1,2 The cells contract, resulting in numerous fine-fold wrinkles and white fibrotic opacities in the posterior capsule. This can reduce visual acuity, contrast sensitivity,3–5 contrast acuity, and stereoscopic vision6,7; cause difficulties with glare8,9 or color vision; or give rise to monocular diplopia. When PCO obscures the visual axis and interferes 258
Q 2011 ASCRS and ESCRS Published by Elsevier Inc.
with visual functions, neodymium:YAG (Nd:YAG) laser capsulotomy is commonly used to restore visual acuity and visual quality. The evaluation of visual functional impairment in relation to the extent of the PCO can be performed using several different tests of visual performance, including psychophysical tests of visual acuity, contrast sensitivity,10,11 glare testing, and forward light scatter combined with or without image-capturing video analysis.12–17 A previous study18 called functional visual acuity 0886-3350/$ - see front matter doi:10.1016/j.jcrs.2010.08.048
FUNCTIONAL VISUAL ACUITY AND POSTERIOR CAPSULE OPACITY
testing an important method of defining “detailed visual function”. The method has been shown to be efficient in detecting “masked impairment of visual function” after cataract surgery in patients with good preoperative and postoperative corrected distance visual acuity (CDVA) and in patients with dry eye who report decreased visual acuity despite normal conventional visual acuity test results. It has also been suggested that functional visual acuity testing is a good indicator of an individual’s performance of certain daily activities, such as driving, reading, and video display terminal work. The purpose of this study was to evaluate the changes in functional visual acuity after Nd:YAG laser capsulotomy in patients with PCO who had 20/20 CDVA with reports of blurred vision. Functional visual acuity was assessed using a new system that measures the recognition acuity continuously over a certain period of time. PATIENTS AND METHODS Patients who had previous cataract surgery and a clinical diagnosis of fibrotic central PCO were recruited into this study. The study adhered to the tenets of the Declaration of Helsinki. The criteria for inclusion were previous uneventful phacoemulsification, presence of fibrotic central PCO, postoperative visual symptoms of blur and glare, a CDVA of at least 20/20, a well-centered posterior chamber intraocular lens (IOL), complete capsulorhexis–IOL overlap, and the ability to perform dynamic function visual acuity testing. No patient had a history of Stevens-Johnson syndrome; chemical, thermal, or radiation injury; ocular inflammation; other systemic/ocular disorders including dry eye; ocular surgery other than cataract
Submitted: July 7, 2010. Final revision submitted: August 19, 2010. Accepted: August 22, 2010.
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surgery; or contact lens use that could cause ocular surface problems.
Patient Assessment All patients had refractive error and CDVA measurements, slitlamp microscopy examinations including evaluation of PCO, high-contrast visual acuity (HCVA), 10% low contrast visual acuity (LCVA), functional visual acuity, wavefront examination, and Schirmer test without anesthesia.
Visual Acuity Measurements
High-contrast (100%) visual acuity was measured at 5 m using a Landolt chart. The chart was retroilluminated by a fluorescent light. Low-contrast visual acuity (10%) was measured at 5 m using a CSV-1000 chart (VectorVision). Changes in visual acuity over time were assessed using the SSC-350 functional visual acuity measurement system (Nidek Co. Ltd.). The system comprises a hard disk, a monitor, and a joystick. It takes continuous measurements starting with the patient’s baseline conventional Landolt CDVA and can measure from 20/10 to 20/2000. In brief, Landolt optotypes are displayed automatically on the monitor, starting with the smaller optotypes. If the responses are incorrect, larger optotypes are automatically presented. When there is no response within 2 seconds, the answer is taken to be an error and the optotype automatically enlarged. In this study, optotypes were presented at 5 m. The presentation time of an optotype was 2 seconds, with the optotypes changing automatically within that time frame. The testing was performed with the patient spontaneously blinking. Patients delineated the orientation of the Landolt rings by using a joystick starting with the baseline CDVA. The measurement at 60 seconds was recorded as the functional visual acuity. The baseline conventional Landolt CDVA was 20/20 or better in all patients. Based on that, the visual maintenance ratio was calculated. The ratio is the logMAR value of the functional visual acuity divided by the logMAR baseline visual acuity score. The lowest logMAR visual acuity score was set at 2.7 for calculation of the visual maintenance ratio as follows: 2.7 – functional visual acuity/2.7 – baseline visual acuity.
Wavefront Aberration
From Johnson & Johnson Department of Ocular Surface and Visual Optics (Wakamatsu, Kaido, Matsumoto, Kojima, Ibrahim, Dogru) and the Department of Ophthalmology (Wakamatsu, Negishi, Kaido, Matsumoto, Kojima, Ibrahim, Saiki, Tsubota), Keio University School of Medicine, Tokyo, the Department of Ophthalmology (Yamaguchi, Dogru), Tokyo Dental College, Chiba, and Ishida Eye Clinic (Ishida), Shizuoka, Japan. Supported in part by research grants from Johnson and Johnson Vision Care Co. Tais Hitomi Wakamatsu, MD, and Takefumi Yamaguchi, MD, contributed equally to this work. Presented at the 60th Congress of Japan Clinical Ophthalmology, Kyoto, Japan, October 2006. Corresponding author: Murat Dogru, MD, Johnson & Johnson Department of Ocular Surface and Visual Optics, Keio University School of Medicine, Shinanomachi 35, Shinjuku-ku, Tokyo 1608582, Japan. E-mail: [email protected].
Wavefront aberration was measured using an ARK-10000 corneal analyzer (Nidek Co., Ltd.) with natural pupil dilation (ie, no cycloplegic agents given) a dim room. The total higher-order aberrations (HOAs) represents the root mean square (RMS) from the 3rd- to 6th-order Zernike coefficient. The RMS of the 3rd-order coefficients was used to represent coma-like aberrations (S3) and the RMS of the 4th-order coefficients, to represent sphericallike aberrations (S4).
Schirmer Test A standard Schirmer test without topical anesthesia was administered. The strips of filter paper (Showa Yakuhin Kako Co. Ltd.) were placed in the lateral canthus away from the cornea and left in place for 5 minutes with the eye closed. Readings were recorded in millimeters of wetting for 5 minutes. A reading of less than 5.0 mm was considered an aqueous tear deficiency.
Surgical Technique After topical anesthesia was administered, a contact lens with a coupling agent was applied to the eye to improve the optics of the laser beam and facilitate accurate focusing. The
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energy level of the Nd:YAG laser unit was set at 1.0 mJ; subsequent shots were applied until the posterior capsule was penetrated. The laser treatment was initiated to form a cross in an approximately 4.0 mm diameter area in the central posterior capsule. If any capsule flap remained in the pupillary space, the laser shot was aimed at the flap. Patients received apraclonidine 1.0% eyedrops soon after the Nd:YAG laser capsulotomy and fluorometholone 0.1% eyedrops 4 times a day for 1 week. Patients returned 1 week later and had repeat testing of preoperative parameters.
Statistical Analysis Decimal visual acuity was converted to a logMAR scale. Functional visual acuity and contrast acuity were converted to the logarithm of inverse values. Data were processed using InStat software (version 3.0, GraphPad Software, Inc.). The logMAR CDVA, functional visual acuity, LCVA, and other continuous variables before and after Nd:YAG laser capsulotomy were compared using the Wilcoxon matched-pairs signed-ranks test. The Spearman correlation analysis was used to determine the correlation between the CDVA, functional visual acuity, LCVA, and HOA RMS before and after Nd:YAG laser capsulotomy. A P value less than 0.05 was considered statistically significant.
RESULTS Ten eyes of 9 patients were enrolled in this study. The mean age of the 4 women and 5 men was 57.3 years G 7.0 (SD) (range 47 to 68 years). Visual Acuity Table 1 shows the mean CDVA, LCVA, functional visual acuity, and visual maintenance ratio before and after Nd:YAG laser capsulotomy. The improvement after Nd:YAG capsulotomy was statistically significant for all parameters except CDVA.
Figure 1 shows the functional visual acuity changes over time for a representative 68-year-old patient. There was a significant improvement in functional visual acuity (from 0.31 to 0.02) 3 weeks after the procedure. The visual maintenance ratio improved from 0.89 before capsulotomy to 0.94 after capsulotomy. Wavefront Aberration The mean natural pupil diameter during wavefront measurements was 3.2 G 0.3 mm (range 3.0 to 4.0 mm) before capsulotomy and 3.1 G 0.1 mm (range 3.0 to 3.4 mm) after capsulotomy. The difference between the 2 periods was not statistically significant (PZ.61). Table 2 shows the changes in HOAs from before to after Nd:YAG capsulotomy. The improvement in HOA RMS and S4 aberration after capsulotomy was statistically significant. The improvement in S3 and the 12th Zernike coefficient was not statistically significant. Correlation Between Visual Acuity and Aberration Figure 2 shows the correlation between S4 and functional visual acuity and S4 and LCVA before and after Nd:YAG capsulotomy. Under photopic conditions, the S4 values were significantly correlated with logMAR LCVA (r Z 0.5183, PZ.0192) and with logMAR functional visual acuity (r Z 0.7369, PZ.0002). The results were similar for the correlation between HOAs and logMAR LCVA (r Z 0.4978, PZ.0301) and between HOAs and logMAR functional visual acuity (r Z 0.5651, PZ.0094) (Figure 3). There was also a statistically significant correlation between logMAR functional visual acuity and logMAR LCVA (r Z 0.7496, PZ.0001) (Figure 4).
Table 1. Visual acuity measurements before and after Nd:YAG laser capsulotomy. Parameter CDVA (logMAR) Mean G SD Range 10% LCVA (logMAR) Mean G SD Range Functional VA (logMAR) Mean G SD Range Visual maintenance ratio Mean G SD Range
Before Capsulotomy
After Capsulotomy
P Value .062
0.05 G 0.06 0.18 to 0.00
0.09 G 0.05 0.08 to 0.18
0.40 G 0.13 0.24 to 0.78
0.22 G 0.12 0.04 to 0.48
0.18 G 0.11 0.03 to 0.46
0.08 G 0.07 0.04 to 0.18
0.92 G 0.02 0.88 to 0.94
0.95 G 0.03 0.91 to 0.99
.003*
.008*
.012*
CDVA Z corrected distance visual acuity; LCVA Z low-contrast visual acuity; VA Z visual acuity *P!.05, Wilcoxon matched-pairs signed-ranks test
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Figure 1. Functional visual acuity results before and after Nd:YAG laser capsulotomy in a 68-year-old woman. Top: The blue line denotes the CDVA before capsulotomy (20/20). The green line denotes the logMAR functional visual acuity (0.31) during the 60-second viewing of the Landolt rings. The red line shows the time-wise change in functional visual acuity during testing. The yellow dots show the number of correct responses. The blue arrows indicate spontaneous blinks. The visual maintenance ratio in this testing was 0.89. Lower: After capsulotomy, there was considerable improvement in functional visual acuity. There was improvement in the mean logMAR functional visual acuity ( 0.02) and the visual maintenance ratio (0.94).
Schirmer Test The mean Schirmer test value was 15.78 G 12.29 mm (range 6.0 to 35.0 mm) before capsulotomy and 13.00 G 11.37 mm (range 7.0 to 35.0 mm) after capsulotomy; the difference was not statistically significant (PO.05). All patients had a Schirmer test value higher than 5.0 mm; none had aqueous tear deficiency. DISCUSSION Previous studies show that PCO significantly decreases HCVA, LCVA, and contrast sensitivity (with and without glare)3–5 as well as stereoacuity6,7 and that there is Table 2. Change in ocular HOAs. Mean RMS (mm) G SD Aberration
Pre Capsulotomy
Post Capsulotomy
P Value
S3 S4 HOA Z12
0.1599 G 0.0856 0.0952 G 0.0537 0.1931 G 0.0908 0.0214 G 0.0373
0.1282 G 0.0624 0.0571 G 0.0378 0.1335 G 0.0771 0.0232 G 0.0206
.0801 .0273* .0137* .5000
HOA Z higher-order aberration; S3 Z 3rd Zernike coefficient (coma like); S4 Z 4th Zernike coefficient (spherical like); Z12Z 12th Zernike coefficient *P!.05, Wilcoxon matched-pairs signed-ranks test
significant improvement in these parameters after Nd:YAG capsulotomy. A previous study5 found that improvement in contrast sensitivity was poorly associated with improvement in visual acuity after Nd:YAG capsulotomy in patients with good visual acuity; the findings suggest that contrast sensitivity is a more informative test than visual acuity in the early stages of PCO. However, findings in another study19 suggest that glare testing provides more information than contrast sensitivity when assessing visual function in patients with PCO. Recent studies report that functional visual acuity testing is a good method of determining impairment of visual function that might not be detectable by other methods as well as a way to assess visual acuity in detail. The usefulness of this new methodology has been described in patients with tear instability,20–22 mild cataract opacities,23 or Steven-Johnson or Sj€ ogren syndrome24 and in patients having laser in situ keratomileusis (LASIK).25 Functional visual acuity measurements are reported to have acceptable reproducibility. A study in which mean functional visual acuity was measured on 2 occasions showed no statistically significant differences between the 2 scores.22 The microstructure of PCO is highly variable; it can take the form of fibrosis, pearls, or both and can range
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in severity and distribution. This variation can affect incident light rays in different ways. The rays can be refracted, reflected, absorbed, or scattered. Even partial PCO can cause the light scattering toward the retina but away from the focused retinal image, allowing good, uniform transmission of light. In these cases, patients have good visual acuity but report disturbances in vision quality. In this study, we used the SSC-350 functional visual acuity measurement system to dynamically assess visual acuity before and after Nd:YAG laser capsulotomy in patients who reported hazy/blurred vision and glare despite having good CDVA before capsulotomy. The mean functional visual acuity improved significantly after Nd:YAG capsulotomy in parallel with an improvement in LCVA. Our results suggest that mild fibrotic PCO with no effect on conventional visual acuity has visually significant implications on dynamic vision measurement even when tear functions are normal. The improvement in functional visual acuity in our study was also associated with an improvement in visual symptoms and contrast visual acuity.
Wavefront testing is another useful way to analyze the correlation between functional visual acuity and ocular aberrations. Studies show the influence of HOAs on visual function in pseudophakic eyes26,27 and post-LASIK eyes.28 Oshika et al.28 found that 4th-order spherical-like aberrations correlated significantly with the changes in 10% LCVA in eyes with a photopic pupil diameter of 4.0 mm or larger. Yamaguchi et al.27 found that the postoperative contrast sensitivity function was significantly correlated with higher-order and 4th-order spherical-like aberrations in pseudophakic eyes under photopic conditions without glare. In our study, there was an improvement in 4th-order spherical-like aberrations and HOAs after Nd:YAG laser capsulotomy, and the improvement was significantly correlated with functional visual acuity and LCVA. Our findings suggest that PCO might have caused the increase in spherical-like and HOAs, which resulted in degradation of visual function, as evidenced by the decreases in functional visual acuity and LCVA in our patients. We believe that functional visual acuity testing can provide information and reflect the effects of HOAs
Figure 2. Correlation between S4 and functional visual acuity (top) and LCVA (bottom) (FVA Z functional visual acuity; LCVA Z low-contrast visual acuity; S4 Z spherical-like aberration).
Figure 3. Correlation between HOAs with logMAR LCVA (top) and logMAR functional visual acuity (bottom) (FVA Z functional visual acuity; HOA Z higher-order aberration; LCVA Z low-contrast visual acuity).
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Figure 4. Correlation between logMAR LCVA and logMAR functional visual acuity (FVA Z functional visual acuity; LCVA Z low-contrast visual acuity).
and/or glare disability on visual function. It is a more thorough assessment of visual disability caused by mild PCO and can also serve as a useful tool in assessing visual quality or justifying the need for Nd:YAG laser capsulotomy in patients with good vision but visual symptoms caused by PCO. REFERENCES 1. McDonnell PJ, Zarbin MA, Green WR. Posterior capsule opacification in pseudophakic eyes. Ophthalmology 1983; 90: 1548–1553 2. Cobo LM, Ohsawa E, Chandler D, Arguello R, George G. Pathogenesis of capsular opacification after extracapsular cataract extraction; an animal model. Ophthalmology 1984; 91:857–863 3. Magno BV, Datiles MB, Lasa MSM, Fajardo MR, Caruso RC, Kaiser-Kupfer MI. Evaluation of visual function following neodymium:YAG laser posterior capsulotomy. Ophthalmology 1997; 104:1287–1293 n L, Beckman C, Sjo € strand J. Glare and 4. Claesson M, Klare contrast sensitivity before and after Nd:YAG laser capsulotomy. Acta Ophthalmol (Copenh) 1994; 72:27–32 5. Hayashi K, Hayashi H, Nakao F, Hayashi F. Correlation between posterior capsule opacification and visual function before and after neodymium:YAG laser posterior capsulotomy. Am J Ophthalmol 2003; 136:720–726 6. Menon GJ, Wong KK, Bundhun T, Ewings P, Twomey JM. The effect of Nd:YAG laser posterior capsulotomy on stereoacuity. Eye 2009; 23:186–189 7. Kwapiszeski BR, Gallagher CC, Holmes JM. Improved stereoacuity: an indication for unilateral cataract surgery. J Cataract Refract Surg 1996; 22:441–445 8. Knighton RW, Slomovic AR, Parrish RK II. Glare measurements before and after neodymium-YAG laser posterior capsulotomy. Am J Ophthalmol 1985; 100:708–713 9. Sunderraj P, Villada JR, Joyce PW, Watson A. Glare testing in pseudophakes with posterior capsule opacification. Eye 1992; 6:411–413
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10. Tan JCH, Spalton DJ, Arden GB. The effect of neodymium:YAG capsulotomy on contrast sensitivity and the evaluation of methods for its assessment. Ophthalmology 1999; 106:703–709 11. Hayashi K, Nakao F, Hayashi H. Influence of size of neodymium:yttrium-aluminium-garnet laser posterior capsulotomy on visual function. Eye 2010; 24:101–106; Availble at: http://www. nature.com/eye/journal/v24/n1/pdf/eye200941a.pdf. Accessed October 14, 2010 12. Hayashi H, Hayashi K, Nakao F, Hayashi F. Quantitative comparison of posterior capsule opacification after polymethylmethacrylate, silicone, and soft acrylic intraocular lens implantation. Arch Ophthalmol 1998; 116:1579–1582. Available at: http:// archopht.ama-assn.org/cgi/reprint/116/12/1579.pdf. Accessed October 14, 2010 13. Hayashi K, Hayashi H, Nakao F, Hayashi F. Reproducibility of posterior capsule opacification measurement using Scheimpflug videophotography. J Cataract Refract Surg 1998; 24:1632–1635 14. Hayashi K, Hayashi H, Nakao F, Hayashi F. In vivo quantitative measurement of posterior capsule opacification after extracapsular cataract surgery. Am J Ophthalmol 1998; 125:837–843 15. Hollick EJ, Spalton DJ, Ursell PG, Pande MV, Barman SA, Boyce JF, Tilling K. The effect of polymethylmethacrylate, silicone, and polyacrylic intraocular lenses on posterior capsular opacification 3 years after cataract surgery. Ophthalmology 1999; 106:49–54; discussion by RC Drews, 54–55 €lcker HE. Photo16. Tetz MR, Auffarth GU, Sperker M, Blum M, Vo graphic image analysis system of posterior capsule opacification. J Cataract Refract Surg 1997; 23:1515–1520 17. Friedman DS, Duncan DD, Munoz B, West SK, Schein OD. Digital image capture and automated analysis of posterior capsular opacification. Invest Ophthalmol Vis Sci 1999; 40:1715– 1726. Available at: http://www.iovs.org/cgi/reprint/40/8/1715. Accessed October 14, 2010 18. Goto E, Yagi Y, Matsumoto Y, Tsubota K. Impaired functional visual acuity of dry eye patients. Am J Ophthalmol 2002; 133:181–186 19. Tan JCH, Spalton DJ, Arden GB. Comparison of methods to assess visual impairment from glare and light scattering with posterior capsule opacification. J Cataract Refract Surg 1998; 24:1626–1631 20. Ishida R, Kojima T, Dogru M, Kaido M, Matsumoto Y, Tanaka M, Goto E, Tsubota K. The application of a new continuous functional visual acuity measurement system in dry eye syndromes. Am J Ophthalmol 2005; 139:253–258 21. Kaido M, Dogru M, Ishida R, Tsubota K. Concept of functional visual acuity and its applications. Cornea 2007; 26(suppl 1): S29–S35 22. Kaido M, Ishida R, Dogru M, Tamaoki T, Tsubota K. Efficacy of punctum plug treatment in short break-up time dry eye. Optom Vis Sci 2008; 85:E758–E763 23. Yamaguchi T, Negishi K, Dogru M, Saiki M, Tsubota K. Improvement of functional visual acuity after cataract surgery in patients with good pre- and postoperative spectacle-corrected visual acuity. J Refract Surg 2009; 25:410–415 24. Kaido M, Dogru M, Yamada M, Sotozono C, Kinoshita S, Shimazaki J, Tsubota K. Functional visual acuity in Stevens-Johnson syndrome. Am J Ophthalmol 2006; 142:917–922 25. Tanaka M, Takano Y, Dogru M, Toda I, Asano-Kato N, KomaiHori Y, Tsubota K. Effect of preoperative tear function on early
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functional visual acuity after laser in situ keratomileusis. J Cataract Refract Surg 2004; 30:2311–2315 26. Hayashi K, Yoshida M, Hayashi H. Correlation of higher-order wavefront aberrations with visual function in pseudophakic eyes. Eye 2008; 22:1476–1482 27. Yamaguchi T, Dogru M, Yamaguchi K, Ono T, Saiki M, Okuyama H, Tsubota K, Negishi K. Effect of spherical aberration on visual function under photopic and mesopic conditions after cataract surgery. J Cataract Refract Surg 2009; 35:57–63 28. Oshika T, Tokunaga T, Samejima T, Miyata K, Kawana K, Kaji Y. Influence of pupil diameter on the relation between ocular higher-order aberration and contrast sensitivity after laser in situ keratomileusis. Invest Ophthalmol Vis Sci 2006; 47:1334–
1338. Available at: http://www.iovs.org/cgi/reprint/47/4/1334. Accessed October 14, 2010
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First author: Takefumi Yamaguchi, MD Department of Ophthalmology, Tokyo Dental College, Chiba, Japan
Functional visual acuity after neodymium:YAG laser capsulotomy in patients with posterior capsule opacification and good visual acuity preoperatively Tais Hitomi Wakamatsu, MD, Takefumi Yamaguchi, MD, Kazuno Negishi, MD, Minako Kaido, MD, Yukihiro Matsumoto, MD, Reiko Ishida, MD, Takashi Kojima, MD, Osama Mohamed Aly Ibrahim, MD, Megumi Saiki, CO, Murat Dogru, MD, Kazuo Tsubota, MD
PURPOSE: To evaluate the changes in functional visual acuity before and after neodymium:YAG (Nd:YAG) laser capsulotomy. SETTING: Keio University Hospital, Tokyo, Japan. DESIGN: Case series. METHODS: Eyes that had previous cataract surgery with a clinical diagnosis of central posterior capsule opacity requiring Nd:YAG laser capsulotomy were evaluated. All patients had refractive error and corrected distance visual acuity (CDVA) measurements; slitlamp microscopy examinations, including posterior capsule opacification evaluation; high-contrast visual acuity measured at 5 m using a Landolt chart; 10% low-contrast visual acuity (LCVA); functional visual acuity; wavefront examination; and a Schirmer test without anesthesia. RESULTS: The study enrolled 9 patients (4 women, 5 men; 10 eyes) with a mean age of 57.3 years G 7.0 (SD) (range 47 to 68 years). Although there was no significant difference in CDVA before and after Nd:YAG capsulotomy, there was a significant improvement in the mean functional visual acuity, from 0.18 G 0.11 logMAR (range 0.03 to 0.31 logMAR) to 0.08 G 0.07 logMAR (range 0.04 to 0.18 logMAR) (P<.05). The LCVA improved significantly after Nd:YAG laser capsulotomy (PZ.003). Higher-order aberrations and the root mean square of the 4th-order coefficients decreased significantly after capsulotomy, and these aberrations were significantly correlated with functional visual acuity and LCVA. CONCLUSION: Results indicate that measurement of functional visual acuity is useful in assessing the quality of vision in patients who have Nd:YAG laser capsulotomy after cataract surgery. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2011; 37:258–264 Q 2011 ASCRS and ESCRS
Posterior capsule opacification (PCO) is one of the most common complications of uneventful cataract surgery. It occurs when lens epithelial cells proliferate and migrate across the posterior capsule.1,2 The cells contract, resulting in numerous fine-fold wrinkles and white fibrotic opacities in the posterior capsule. This can reduce visual acuity, contrast sensitivity,3–5 contrast acuity, and stereoscopic vision6,7; cause difficulties with glare8,9 or color vision; or give rise to monocular diplopia. When PCO obscures the visual axis and interferes 258
Q 2011 ASCRS and ESCRS Published by Elsevier Inc.
with visual functions, neodymium:YAG (Nd:YAG) laser capsulotomy is commonly used to restore visual acuity and visual quality. The evaluation of visual functional impairment in relation to the extent of the PCO can be performed using several different tests of visual performance, including psychophysical tests of visual acuity, contrast sensitivity,10,11 glare testing, and forward light scatter combined with or without image-capturing video analysis.12–17 A previous study18 called functional visual acuity 0886-3350/$ - see front matter doi:10.1016/j.jcrs.2010.08.048
FUNCTIONAL VISUAL ACUITY AND POSTERIOR CAPSULE OPACITY
testing an important method of defining “detailed visual function”. The method has been shown to be efficient in detecting “masked impairment of visual function” after cataract surgery in patients with good preoperative and postoperative corrected distance visual acuity (CDVA) and in patients with dry eye who report decreased visual acuity despite normal conventional visual acuity test results. It has also been suggested that functional visual acuity testing is a good indicator of an individual’s performance of certain daily activities, such as driving, reading, and video display terminal work. The purpose of this study was to evaluate the changes in functional visual acuity after Nd:YAG laser capsulotomy in patients with PCO who had 20/20 CDVA with reports of blurred vision. Functional visual acuity was assessed using a new system that measures the recognition acuity continuously over a certain period of time. PATIENTS AND METHODS Patients who had previous cataract surgery and a clinical diagnosis of fibrotic central PCO were recruited into this study. The study adhered to the tenets of the Declaration of Helsinki. The criteria for inclusion were previous uneventful phacoemulsification, presence of fibrotic central PCO, postoperative visual symptoms of blur and glare, a CDVA of at least 20/20, a well-centered posterior chamber intraocular lens (IOL), complete capsulorhexis–IOL overlap, and the ability to perform dynamic function visual acuity testing. No patient had a history of Stevens-Johnson syndrome; chemical, thermal, or radiation injury; ocular inflammation; other systemic/ocular disorders including dry eye; ocular surgery other than cataract
Submitted: July 7, 2010. Final revision submitted: August 19, 2010. Accepted: August 22, 2010.
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surgery; or contact lens use that could cause ocular surface problems.
Patient Assessment All patients had refractive error and CDVA measurements, slitlamp microscopy examinations including evaluation of PCO, high-contrast visual acuity (HCVA), 10% low contrast visual acuity (LCVA), functional visual acuity, wavefront examination, and Schirmer test without anesthesia.
Visual Acuity Measurements
High-contrast (100%) visual acuity was measured at 5 m using a Landolt chart. The chart was retroilluminated by a fluorescent light. Low-contrast visual acuity (10%) was measured at 5 m using a CSV-1000 chart (VectorVision). Changes in visual acuity over time were assessed using the SSC-350 functional visual acuity measurement system (Nidek Co. Ltd.). The system comprises a hard disk, a monitor, and a joystick. It takes continuous measurements starting with the patient’s baseline conventional Landolt CDVA and can measure from 20/10 to 20/2000. In brief, Landolt optotypes are displayed automatically on the monitor, starting with the smaller optotypes. If the responses are incorrect, larger optotypes are automatically presented. When there is no response within 2 seconds, the answer is taken to be an error and the optotype automatically enlarged. In this study, optotypes were presented at 5 m. The presentation time of an optotype was 2 seconds, with the optotypes changing automatically within that time frame. The testing was performed with the patient spontaneously blinking. Patients delineated the orientation of the Landolt rings by using a joystick starting with the baseline CDVA. The measurement at 60 seconds was recorded as the functional visual acuity. The baseline conventional Landolt CDVA was 20/20 or better in all patients. Based on that, the visual maintenance ratio was calculated. The ratio is the logMAR value of the functional visual acuity divided by the logMAR baseline visual acuity score. The lowest logMAR visual acuity score was set at 2.7 for calculation of the visual maintenance ratio as follows: 2.7 – functional visual acuity/2.7 – baseline visual acuity.
Wavefront Aberration
From Johnson & Johnson Department of Ocular Surface and Visual Optics (Wakamatsu, Kaido, Matsumoto, Kojima, Ibrahim, Dogru) and the Department of Ophthalmology (Wakamatsu, Negishi, Kaido, Matsumoto, Kojima, Ibrahim, Saiki, Tsubota), Keio University School of Medicine, Tokyo, the Department of Ophthalmology (Yamaguchi, Dogru), Tokyo Dental College, Chiba, and Ishida Eye Clinic (Ishida), Shizuoka, Japan. Supported in part by research grants from Johnson and Johnson Vision Care Co. Tais Hitomi Wakamatsu, MD, and Takefumi Yamaguchi, MD, contributed equally to this work. Presented at the 60th Congress of Japan Clinical Ophthalmology, Kyoto, Japan, October 2006. Corresponding author: Murat Dogru, MD, Johnson & Johnson Department of Ocular Surface and Visual Optics, Keio University School of Medicine, Shinanomachi 35, Shinjuku-ku, Tokyo 1608582, Japan. E-mail: [email protected].
Wavefront aberration was measured using an ARK-10000 corneal analyzer (Nidek Co., Ltd.) with natural pupil dilation (ie, no cycloplegic agents given) a dim room. The total higher-order aberrations (HOAs) represents the root mean square (RMS) from the 3rd- to 6th-order Zernike coefficient. The RMS of the 3rd-order coefficients was used to represent coma-like aberrations (S3) and the RMS of the 4th-order coefficients, to represent sphericallike aberrations (S4).
Schirmer Test A standard Schirmer test without topical anesthesia was administered. The strips of filter paper (Showa Yakuhin Kako Co. Ltd.) were placed in the lateral canthus away from the cornea and left in place for 5 minutes with the eye closed. Readings were recorded in millimeters of wetting for 5 minutes. A reading of less than 5.0 mm was considered an aqueous tear deficiency.
Surgical Technique After topical anesthesia was administered, a contact lens with a coupling agent was applied to the eye to improve the optics of the laser beam and facilitate accurate focusing. The
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energy level of the Nd:YAG laser unit was set at 1.0 mJ; subsequent shots were applied until the posterior capsule was penetrated. The laser treatment was initiated to form a cross in an approximately 4.0 mm diameter area in the central posterior capsule. If any capsule flap remained in the pupillary space, the laser shot was aimed at the flap. Patients received apraclonidine 1.0% eyedrops soon after the Nd:YAG laser capsulotomy and fluorometholone 0.1% eyedrops 4 times a day for 1 week. Patients returned 1 week later and had repeat testing of preoperative parameters.
Statistical Analysis Decimal visual acuity was converted to a logMAR scale. Functional visual acuity and contrast acuity were converted to the logarithm of inverse values. Data were processed using InStat software (version 3.0, GraphPad Software, Inc.). The logMAR CDVA, functional visual acuity, LCVA, and other continuous variables before and after Nd:YAG laser capsulotomy were compared using the Wilcoxon matched-pairs signed-ranks test. The Spearman correlation analysis was used to determine the correlation between the CDVA, functional visual acuity, LCVA, and HOA RMS before and after Nd:YAG laser capsulotomy. A P value less than 0.05 was considered statistically significant.
RESULTS Ten eyes of 9 patients were enrolled in this study. The mean age of the 4 women and 5 men was 57.3 years G 7.0 (SD) (range 47 to 68 years). Visual Acuity Table 1 shows the mean CDVA, LCVA, functional visual acuity, and visual maintenance ratio before and after Nd:YAG laser capsulotomy. The improvement after Nd:YAG capsulotomy was statistically significant for all parameters except CDVA.
Figure 1 shows the functional visual acuity changes over time for a representative 68-year-old patient. There was a significant improvement in functional visual acuity (from 0.31 to 0.02) 3 weeks after the procedure. The visual maintenance ratio improved from 0.89 before capsulotomy to 0.94 after capsulotomy. Wavefront Aberration The mean natural pupil diameter during wavefront measurements was 3.2 G 0.3 mm (range 3.0 to 4.0 mm) before capsulotomy and 3.1 G 0.1 mm (range 3.0 to 3.4 mm) after capsulotomy. The difference between the 2 periods was not statistically significant (PZ.61). Table 2 shows the changes in HOAs from before to after Nd:YAG capsulotomy. The improvement in HOA RMS and S4 aberration after capsulotomy was statistically significant. The improvement in S3 and the 12th Zernike coefficient was not statistically significant. Correlation Between Visual Acuity and Aberration Figure 2 shows the correlation between S4 and functional visual acuity and S4 and LCVA before and after Nd:YAG capsulotomy. Under photopic conditions, the S4 values were significantly correlated with logMAR LCVA (r Z 0.5183, PZ.0192) and with logMAR functional visual acuity (r Z 0.7369, PZ.0002). The results were similar for the correlation between HOAs and logMAR LCVA (r Z 0.4978, PZ.0301) and between HOAs and logMAR functional visual acuity (r Z 0.5651, PZ.0094) (Figure 3). There was also a statistically significant correlation between logMAR functional visual acuity and logMAR LCVA (r Z 0.7496, PZ.0001) (Figure 4).
Table 1. Visual acuity measurements before and after Nd:YAG laser capsulotomy. Parameter CDVA (logMAR) Mean G SD Range 10% LCVA (logMAR) Mean G SD Range Functional VA (logMAR) Mean G SD Range Visual maintenance ratio Mean G SD Range
Before Capsulotomy
After Capsulotomy
P Value .062
0.05 G 0.06 0.18 to 0.00
0.09 G 0.05 0.08 to 0.18
0.40 G 0.13 0.24 to 0.78
0.22 G 0.12 0.04 to 0.48
0.18 G 0.11 0.03 to 0.46
0.08 G 0.07 0.04 to 0.18
0.92 G 0.02 0.88 to 0.94
0.95 G 0.03 0.91 to 0.99
.003*
.008*
.012*
CDVA Z corrected distance visual acuity; LCVA Z low-contrast visual acuity; VA Z visual acuity *P!.05, Wilcoxon matched-pairs signed-ranks test
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Figure 1. Functional visual acuity results before and after Nd:YAG laser capsulotomy in a 68-year-old woman. Top: The blue line denotes the CDVA before capsulotomy (20/20). The green line denotes the logMAR functional visual acuity (0.31) during the 60-second viewing of the Landolt rings. The red line shows the time-wise change in functional visual acuity during testing. The yellow dots show the number of correct responses. The blue arrows indicate spontaneous blinks. The visual maintenance ratio in this testing was 0.89. Lower: After capsulotomy, there was considerable improvement in functional visual acuity. There was improvement in the mean logMAR functional visual acuity ( 0.02) and the visual maintenance ratio (0.94).
Schirmer Test The mean Schirmer test value was 15.78 G 12.29 mm (range 6.0 to 35.0 mm) before capsulotomy and 13.00 G 11.37 mm (range 7.0 to 35.0 mm) after capsulotomy; the difference was not statistically significant (PO.05). All patients had a Schirmer test value higher than 5.0 mm; none had aqueous tear deficiency. DISCUSSION Previous studies show that PCO significantly decreases HCVA, LCVA, and contrast sensitivity (with and without glare)3–5 as well as stereoacuity6,7 and that there is Table 2. Change in ocular HOAs. Mean RMS (mm) G SD Aberration
Pre Capsulotomy
Post Capsulotomy
P Value
S3 S4 HOA Z12
0.1599 G 0.0856 0.0952 G 0.0537 0.1931 G 0.0908 0.0214 G 0.0373
0.1282 G 0.0624 0.0571 G 0.0378 0.1335 G 0.0771 0.0232 G 0.0206
.0801 .0273* .0137* .5000
HOA Z higher-order aberration; S3 Z 3rd Zernike coefficient (coma like); S4 Z 4th Zernike coefficient (spherical like); Z12Z 12th Zernike coefficient *P!.05, Wilcoxon matched-pairs signed-ranks test
significant improvement in these parameters after Nd:YAG capsulotomy. A previous study5 found that improvement in contrast sensitivity was poorly associated with improvement in visual acuity after Nd:YAG capsulotomy in patients with good visual acuity; the findings suggest that contrast sensitivity is a more informative test than visual acuity in the early stages of PCO. However, findings in another study19 suggest that glare testing provides more information than contrast sensitivity when assessing visual function in patients with PCO. Recent studies report that functional visual acuity testing is a good method of determining impairment of visual function that might not be detectable by other methods as well as a way to assess visual acuity in detail. The usefulness of this new methodology has been described in patients with tear instability,20–22 mild cataract opacities,23 or Steven-Johnson or Sj€ ogren syndrome24 and in patients having laser in situ keratomileusis (LASIK).25 Functional visual acuity measurements are reported to have acceptable reproducibility. A study in which mean functional visual acuity was measured on 2 occasions showed no statistically significant differences between the 2 scores.22 The microstructure of PCO is highly variable; it can take the form of fibrosis, pearls, or both and can range
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in severity and distribution. This variation can affect incident light rays in different ways. The rays can be refracted, reflected, absorbed, or scattered. Even partial PCO can cause the light scattering toward the retina but away from the focused retinal image, allowing good, uniform transmission of light. In these cases, patients have good visual acuity but report disturbances in vision quality. In this study, we used the SSC-350 functional visual acuity measurement system to dynamically assess visual acuity before and after Nd:YAG laser capsulotomy in patients who reported hazy/blurred vision and glare despite having good CDVA before capsulotomy. The mean functional visual acuity improved significantly after Nd:YAG capsulotomy in parallel with an improvement in LCVA. Our results suggest that mild fibrotic PCO with no effect on conventional visual acuity has visually significant implications on dynamic vision measurement even when tear functions are normal. The improvement in functional visual acuity in our study was also associated with an improvement in visual symptoms and contrast visual acuity.
Wavefront testing is another useful way to analyze the correlation between functional visual acuity and ocular aberrations. Studies show the influence of HOAs on visual function in pseudophakic eyes26,27 and post-LASIK eyes.28 Oshika et al.28 found that 4th-order spherical-like aberrations correlated significantly with the changes in 10% LCVA in eyes with a photopic pupil diameter of 4.0 mm or larger. Yamaguchi et al.27 found that the postoperative contrast sensitivity function was significantly correlated with higher-order and 4th-order spherical-like aberrations in pseudophakic eyes under photopic conditions without glare. In our study, there was an improvement in 4th-order spherical-like aberrations and HOAs after Nd:YAG laser capsulotomy, and the improvement was significantly correlated with functional visual acuity and LCVA. Our findings suggest that PCO might have caused the increase in spherical-like and HOAs, which resulted in degradation of visual function, as evidenced by the decreases in functional visual acuity and LCVA in our patients. We believe that functional visual acuity testing can provide information and reflect the effects of HOAs
Figure 2. Correlation between S4 and functional visual acuity (top) and LCVA (bottom) (FVA Z functional visual acuity; LCVA Z low-contrast visual acuity; S4 Z spherical-like aberration).
Figure 3. Correlation between HOAs with logMAR LCVA (top) and logMAR functional visual acuity (bottom) (FVA Z functional visual acuity; HOA Z higher-order aberration; LCVA Z low-contrast visual acuity).
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Figure 4. Correlation between logMAR LCVA and logMAR functional visual acuity (FVA Z functional visual acuity; LCVA Z low-contrast visual acuity).
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First author: Takefumi Yamaguchi, MD Department of Ophthalmology, Tokyo Dental College, Chiba, Japan