The changing nature and higher demands of today’s cataract surgery patient continue to push both surgeons and manufacturers toward achieving excellence. This year’s ARVO abstracts represent a wide range of international efforts to understand the issues that impact surgery and develop products and techniques to improve it.

Unless otherwise stated, none of the studies presented here had any commercial support.

General Surgical Issues

While studies have addressed complication rates in cataract surgery, a group at King’s College Hospital, London, cited a lack of data on the relationship between specific pre-existing conditions and complications. They conducted a large study to determine whether pre-existing ocular conditions increase the risk of mild, moderate or severe complications and to quantify any such relationships.

Over three years of cataract operations performed at King’s College Hospital, they recorded pre-existing ocular conditions and surgery outcome. Operations with no pre-existing conditions served as controls. All others were grouped according to condition type. The frequencies of mild, moderate and severe complications in each group were compared with control using a chi-squared test. Relative risks (RR) were then calculated for each statistically significant result (p<0.05).

The study included 7,702 control operations (complication rate, 2.64 percent) and 2,071 operations with pre-existing ocular conditions (complication rate, 6.81 percent). The risk of mild complications was significantly increased by pre-existing uveitis/synechiae (RR 3.69), pseudoexfoliation/phacodonesis (RR 6.22), brunescent/white cataract (RR 7.46), high myopia (RR 2.64), diabetic retinopathy (RR 3.12) or previous vitrectomy (RR 9.54).
The risk of moderate complications was significantly increased by corneal pathology (RR 2.94), pseudoexfoliation/phacodonesis (RR 8.89), brunescent/white cataract (RR 6.43) or reduced fundus view/vitreous opacities (RR 8.79). The risk of severe complications was significantly increased by brunescent/white cataract only, with RR of 15.97.

The researchers hope the results of this study will enable surgeons to provide more individualized counseling to patients before undergoing cataract surgery.5392

Researchers at two New York City institutions report a study showing that optical biometry can be performed on the initial cataract evaluation visit, and reduce the need for an additional visit for biometry. Because dilation and examination of the eye can result in differences in biometry, the belief exists that precise preoperative measurements should be based on a pre-examined eye, requiring a return visit to complete the preoperative assessment.

In 80 phakic eyes from 47 patients ages 60 and above, the group evaluated the effects of pupillary dilation, applanation tonometry and slit-lamp examination on IOLMaster (Zeiss) biometry, axial length, anterior chamber depth, and corneal K values, with additional evaluation of test-retest variability. From this group, a control group of 30 eyes from 17 patients underwent an additional set of pre-examination IOLMaster measurements. SRK/T formula was used to calculate IOL power and refractive error for Alcon MTA4UO and Acrysof lenses. Refractive errors in the post-examined eye were also calculated by matching post-examined plano IOL power to the pre-examined eye refractive error data, to assess refraction when using the IOL power attained post-dilation and examination.

The IOLMaster showed a high level of reproducibility between pre-examination and control groups as well as between pre- and post-examination groups. Mean refractive error in the examined group was 0.2 for the MTA4UO lens compared to an unexamined group mean refraction of 0.1 (p=0.0002) and control of 0.13. For MTA4UO, the mean difference in refractive error between unexamined and examined groups was 0.21, compared to 0.15 between unexamined and control groups. Similar results were obtained for Alcon AcrySof. Differences in axial length, anterior chamber depth, K1 and K2 were negligible in all three groups.5409

Surgeons in Austria report a study they say clearly shows that surgically induced astigmatism is statistically significantly lower in the coaxial micro-phaco surgery than in small-incision cataract surgery, resulting in better UCVA, at least up to four weeks after surgery.

Their prospective study compared higher-order aberrations and surgically induced astigmatism between coaxial micro-phacoemulsification (Co-MICS) and small-incision cataract surgery (SICS) in 77 eyes of 51 patients implanted with AcrySof IQ aspheric IOLs; 46 eyes underwent Co-MICS (2.2-mm incision) and 31 eyes SICS (3-mm incision). After phacoemulsification through a temporal clear cornea incision all eyes received an AcrySof IQ posterior chamber lens. UCVA and BSCVA were determined preoperatively, at day one and at two and four weeks postop. Corneal topography using Orbscan II and refractometry were performed to calculate SIA. All eyes underwent wavefront analysis.

No statistically significant difference was found in age, sex, mean preop BSCVA and other preop ocular characteristics between the groups. Four weeks postop SIA was statistically significantly higher (p<0.005) in the SICS group (1.14 ±0.685 D) than in the Co-MICS group (0.820 ±0.504 D). At four months postop, 34.5 percent of eyes in the Co-MICS group achieved a UCVA of 20/20 or better versus 15.8 percent in the SICS group (p<0.05).

Spherical aberrations statistically significantly decreased both in the Co-MICS group from 0.119 ±0.084 (mean ±SD) preop to 0.043 ±0.035 (mean ±SD) postop (p=0.009) and in the SICS group from 0.172 ±0.114 (mean ±SD) preop to 0.056 ±0.053 (mean ±SD) postop (p=0.018). Although there was a minimal reduction in coma and trefoil in both groups postoperatively, no statistically significant differences pre-and four weeks postoperatively were detected between the groups.5404

A group from Barcelona, Spain, and Salzburg, Austria, analyzed the factors that influence visual quality after posterior capsulotomy by studying the correlation between posterior capsule opacification (PCO) and measured intraocular straylight and visual acuity.

Visual acuity (logMAR) and intraocular straylight were measured under photopic conditions before and two weeks after YAG capsulotomy in 53 eyes (41 patients).
Photopic pupil diameter was measured. To document the amount of opacification, pupils were dilated and photographs were taken at a slit lamp, using retroillumination and the reflected-light of a wide slit beam at an angle of 45 degrees focused on the posterior capsule. PCO was subjectively graded on a scale from 1 to 10.

Straylight showed a good correlation with retroillumination and reflected-light PCO grading whereas VA only correlated with retroillumination. Both VA and straylight improved after capsulotomy. Straylight values presented a large variation after capsulotomy. Multiple regression analysis showed that increasing age and ocular axial length, hydrophobic acrylic IOLs and small capsulotomies are factors that increased intraocular straylight.

The group deems intraocular straylight to be a useful tool that correlates well with PCO severity grading methods. When performing a posterior capsulotomy, surgeons should consider factors such as age, IOL material, axial length and capsulotomy size, as they have an influence on intraocular straylight, they conclude.5425

Intraocular Lenses

Research at Montreal’s McGill University reports high spectacle independence following toric IOL implantation.

The telephone survey questionnaire recorded: frequency of postop spectacle wear (always, often or never); patient satisfaction without glasses (scale 1 to 10); frequency of glare (scale 0 to 4); and whether patients would select the same lens again. All patients had uncomplicated, SN60T3 toric IOL implantation in both eyes. A total of 38 patients agreed to participate, 25 males and 13 females with an age range from 51 to 83 years, mean 67 years. The key findings:

    • 36 (95 percent) patients wore spectacles before the surgery and seven (18 percent) patients wear spectacles after the surgery (four of them wear the spectacles all the time, three patients, sometimes.)

    • 26 (68.4 percent) patients report a 10/10 satisfaction score; seven (18.4 percent) report 9/10; three (7.9 percent) report 8/10 and two (5.3 percent) patients report less than 6/10.

    • 35 (92.1 percent) patients report no glare (0/4 on the glare scale), two (5.3 percent) report 2/4 glare and one (2.6 percent) patient has 3/4 glare.

    • 36 patients would choose the same lens again, two would not.

Those patients who wear glasses postoperatively or gave a satisfaction score less than 6/10 or 3/4 on the glare scale or who would not choose the same lens again had spherical refractive error (-1.5 to +1.25 D) and astigmatic error ranging from 0.25 to 0.75 D.

Those patients who needed glasses did so due to spherical ametropia and not due to astigmatism, the group concludes. The unfavorable postoperative symptoms (e.g. glare and night vision difficulties) were no different from those published after monofocal intra- ocular lens implantation. The availability of higher cylinder correction should increase patient satisfaction levels further.4568

From South Carolina’s Storm Eye Institute, a precaution about clinical trial results vs. real-world clinical practice. Researchers at Storm divided 112 patients that received bilateral multifocal IOLs into two groups; one group (n=32) included clinical trial participants; the second group (n=80) comprised non-participants. They then assessed satisfaction by overall (OS), distance (DS), intermediate (IS), near (NS) and night-vision satisfaction (NTVS) using a scale from 0 (very dissatisfied) to 10 (highly satisfied).

No significant difference was seen in age, residual error, postoperative VA (uncorrected or best-corrected) at distance, intermediate and near between groups. NS was significantly higher in clinical trial patients-CTP (8.5 vs. 7.9. p=0.015). Although trial participants showed overall higher satisfaction scores, no significant differences were found in other parameters.4572

Scientists at the University of Rochester and the University of Ulsan, Seoul, South Korea, developed an optical bench system and model eye to measure the effects of chromatic aberration and corneal astigmatism on retinal image quality (RIQ) and depth of focus (DoF) of accommodating and multifocal premium IOLs.

The model eye consisted of a wet cell with an artificial cornea (0.085 µm spherical aberration for 4-mm pupil) and an IOL mounted with decenter capability. Ophthalmic trial lenses were placed before the artificial cornea to simulate corneal astigmatism (up to 1 D) and varying object distance (up to 5 D). Tested lenses included the aspheric accommodating Crystalens HD, and the aspheric diffractive multifocals Alcon ReSTOR 3D and Tecnis ZM900. The AcrySof SN60AT spherical monofocal served as a control.
All IOLs had 20-D power and were tested with a 4-mm pupil. RIQ was determined by measuring the contrast of images of a poly- and monochromatically illuminated USAF resolution target at spatial frequencies of 30 and 15 cycles per degree (cpd), corresponding to 20/20 and 20/40 Snellen letter sizes, respectively. DoF was defined as the dioptric range with RIQ at 15 cpd greater than 50 percent of peak RIQ for AcrySof.

The AcrySof had the best RIQ but was limited to distance vision (0 to 1 D). Crystalens HD extended its DoF by 30 percent compared to the AcrySof. Multifocal IOLs sacrificed distant RIQ (60 percent that of AcrySof) for extended DoF with the addition of near vision, however they lacked intermediate vision. Chromatic aberration had a detrimental effect on RIQ for all lenses. ReSTOR and Tecnis were impacted less than the AcrySof and Crystalens due to their inherently lower RIQ at distance vision. For up to 700 µm decentration, changes in RIQ of white-light images for all IOLs were insignificant.
Corneal astigmatism also reduced RIQ for all IOLs. DoF was not decreased with astigmatism up to 0.25 D for Tecnis, although RIQ at 15 cpd decreased by 5 percent. DoF was not decreased with astigmatism up to 0.5 D for AcrySof (35-percent RIQ decrease), Crystalens (28-percent RIQ decrease) and ReSTOR (4-percent RIQ decrease). With corneal astigmatism larger than 0.5 D, DoF for the premium IOLs did not significantly differ from that with AcrySof.

The clinical message of the study, say the authors, is that the benefit of extended depth of focus with premium IOLs is absent in the presence of corneal astigmatism larger than 0.5 D. The uncorrected corneal astigmatism in pseudophakic patients can affect through focus performance of premium IOLs and needs to be compensated to maximize their efficacy.5725

From the University of Tuebingen, Germany, a prospective, double-masked multicenter study compared the new Tecnis multifocal diffractive ZMB00 one-piece hydrophobic acrylic lens (near addition +4 D) with the Tecnis monofocal model ZCB00 one-piece hydrophobic acrylic lens. Either the Tecnis one-piece multifocal IOL (n=35) or the monofocal Tecnis one-piece IOLs (n=35) were bilaterally implanted in patients with cataract. Masked follow-up examinations were performed one day, one week, one to two months and four to six months after surgery and comprised refraction, monocular and binocular visual acuity (near and distance with ETDRS), Radner reading speed, defocus curve, pupil size, keratometry and slit-lamp biomicroscopy.

The first eight eyes finished the four-week follow-up: After one week all multifocal patients achieved UCDVA of 20/25 or better having an average spherical equivalent within ±0.2 D. After four weeks UCDVA improved to 20/20 or better and also the UCNVA was 20/25 or better in all eyes with an average spherical equivalent within ±0.3 D. All multifocal patients showed  high satisfaction and comfort due to spectacle-free near and distance vision. Three patients reported mild halos with no disturbance. Complications and optical visual symptoms were low and comparable to the monofocal IOL group.

The first results indicate that the new multifocal IOL based on the proven concept of a one-piece hydrophobic acrylic IOL design combines the advantages of ease of implantation and low complication rate with the benefit of reduced spectacle dependency, the authors conclude.5724

Researchers at the University of Illinois and the University of North Carolina sought to determine if preoperative or postoperative characteristics are predictive of pseudophakic pseudoaccommodation (PP). In their study, 44 subjects over age 60 with cataracts and best corrected distance visual acuity (BCDVA) better than 20/80 underwent uncomplicated bimanual microincision phacoemulsification with monofocal pcIOL placement. Preoperative BCDVA, distance-corrected near visual acuity, and video keratoscopy including simulated keratometry and vertical coma were recorded. One month postop, uncorrected distance and near VA were recorded and all preop measurements were repeated. Patients with UCDVA 20/40 or better and UCNVA 20/40 or better were classified as having pseudophakic pseudoaccommodation. Six outcome measures were assessed: cylinder, orientation of astigmatism, spherical equivalent, the difference between steep and flat meridians by simK (simK difference), orientation of steep meridian by simK, and vertical coma. Statistical analysis compared the outcome measures between patients with and without PP. Hypothesized values for each of the outcome measures that would be beneficial for PP were proposed and tested.

Pseudophakic pseudoaccommodation was present in 10 patients, and the preoperative simK difference was significantly lower in this group (p=0.01). Other measures demonstrated no significant difference. Patients with pseudoaccommodation were hypothesized to have more negative vertical coma (≤-0.20 µm) than patients without. Fisher’s exact test confirmed this association (p=0.043). No other hypotheses were statistically significant.

Overall, 23 percent of patients demonstrated pseudophakic pseudoaccommodation, a greater percentage than has been reported in previous studies. Preoperatively, the patients with PP had less difference between the two simK powers (0.51 vs. 0.93 D), indicating that greater corneal astigmatism may be detrimental to pseudoaccommodation.
It is known that astigmatism increases depth of focus, but larger amounts may degrade the quality of vision excessively. The group says the results support previous studies linking pseudoaccommodation with more negative vertical coma. This may provide some degree of corneal multifocality, increasing depth of focus.5736

Cataract Surgery and Dry Eye

Postop dry eye in cataract patients is receiving increasing attention, as evidenced by a study at the University of Genoa, Italy. Researchers there investigated symptoms of dry eye and signs of ocular surface damage in 40 normal subjects who underwent phacoemulsification and cataract surgery with a 2.75-mm temporal incision. Collected data included OSDI Questionnaire, Schirmer I test, tear breakup time, lissamine green conjunctival staining (NEI scoring system), and fluorescein corneal staining before surgery and one, seven, 30 and 60 days postop. The Dynamic Lipid Interference Pattern test was used to quantify tear-film stability at each follow-up.

Statistically significant changes in symptoms, corneal fluorescein staining, lissamine green conjunctival staining, BUT and DLIP occurred in the study group at day one and seven. At day 30, changes were evident compared to baseline for BUT and DLIP, and at day 60 for DLIP only. Schirmer test did not show any significant changes throughout the study. The study indicates that cataract surgery may induce a clinical picture similar to dry eye, pointing out possible risks in patients with previous ocular surface diseases, the group concludes.6254

Infection Control

A retrospective study at the Uni-versity of Freiburg, Germany, challenges some of the recommendations of the 2006 ESCRS Endophthalmitis Study. The study identified all cases of postop endophthalmitis that were diagnosed both clinically and microbiologically in patients undergoing cataract surgery over a 12-year period at a single medical center. The center used a protocol of preoperative topical povidone-iodine and a gentamicin-containing irrigation fluid as prophylaxis without intracameral cefuroxime or postoperative topical levofloxacin.

A total of 26,566 cataract procedures were reviewed, and 16 cases with postoperative endophthalmitis identified (0.06 percent). A causative micro-organism was detected in 81.3 percent (13/16) of the cases. Most organisms were gram-positive bacteria (10/13) with susceptibility to cefuroxime (9/10) and/or fluoroquinolones (4/8), and/or resistance to aminoglycosides (10/10). The three gram-negative pathogens were susceptible to cefuroxime, aminoglycosides and fluoroquinolones.

Using the protocol described, a low rate of postop endophthalmitis was observed that was not much different from the infection rates reported in the ESCRS study (i.e. 0.5 and 0.7 per 1,000 for patients given intracameral cefuroxime with and without levofloxacin eyedrops, respectively). The group suggests neither intracameral cefuroxime nor postoperative levofloxacin eyedrops are needed to minimize postop infectious complications, and suggests that the ESCRS guidelines should be substantially revised to allow alternative effective regimens for the prevention of postoperative infections following cataract surgery.5387

Seidel testing for wound instability has a limited role in prognostication of endophthalmitis, according to a study at New York University. The prospective study included all consecutive cataract patients of three resident surgeons over a five-month period (94 cases, 89 phacoemulsifications and five extracaps). All patients underwent extensive wound testing at the end of surgery with documentation of water-tight seals. Patients returned for postop day one examination, when wound stability was assessed by Seidel testing to look for spontaneous leakage, as well as leakage induced by forceful blinking and globe compression superior temporally. Other clinical information gathered: VA, intraocular pressure, grading of anterior chamber inflammation, degree of corneal edema and details of postoperative course.

Wound leaks were identified in three (3.3 percent) phaco cases and two (40 percent) ECCE cases. All five wound leaks were spontaneously positive. No additional cases were identified by testing with vigorous blinking or with globe compression. While the average IOP of non-wound leak cases, 23.9 mmHg, differed significantly from cases with positive leaks, 10.2 mmHg (p<0.05), high IOP did not preclude the possibility of wound leakage. Wound leak cases did not differ significantly in terms of VA, anterior chamber grading of inflammation or presence of corneal edema. One case of endophthalmitis was identified at postop day four, which did not have a wound leak at postop day one, though the clear corneal incision was enlarged from 2.75 mm to 4.1 mm intraoperatively. Additional assessment with blinking and globe compression did not yield any additional helpful information. The researchers say a new modality of postoperative testing is needed to assess wound stability to better stratify risk of postoperative complications for improved preventive treatment.5424

Dr. Blecher is co-director of the Cataract Service at Wills Eye Institute and is in private practice in Philadelphia.