Herbert Weghaupt

Halo size under distance and near conditions in refractive multifocal intraocular lenses

AIMS To calculate the diameter of halos perceived by patients with multifocal intraocular lenses (IOLs) and to stimulate halos in patients with refractive multifocal IOLs in a clinical experiment. METHODS Calculations were done to show the diameter of halos in the case of the bifocal intraocular lens. 24 patients with a refractive multifocal IOLs and five patients with a monofocal IOL were asked about their subjective observation of halos and were included in a clinical experiment using a computer program (Glare & Halo, FW Fitzke and C Lohmann, Tomey AG) which simulates a light source of 0.15 square degrees (sq deg) in order to stimulate and measure halos. Halo testing took place monoculary, under mesopic conditions through the distance and the near focus of the multifocal lens and through the focus of the monofocal lens. RESULTS The halo diameter depends on the pupil diameter, the refractive power of the cornea, and distance focus of the multifocal IOL as well as the additional lens power for the near focus. 23 out of 24 patients with a refractive multifocal IOL described halos at night when looking at a bright light source. Only one patient was disturbed by the appearance of halos. Under test conditions, halos were detected in all patients with a refractive multifocal IOL. The halo area testing through the distance focus was 1.05 sq deg ± 0.41, through the near focus 1.07 sq deg ± 0.49 and in the monofocal lens 0.26 sq deg ± 0.13. CONCLUSIONS Under high contrast conditions halos can be stimulated in all patients with multifocal intraocular lenses. The halo size using the distance or the near focus is identical.

Topical versus peribulbar anesthesia in clear corneal cataract surgery

Purpose: To evaluate the efficacy of topical anesthesia as an alternative to peribulbar anesthesia in clear corneal cataract surgery. Setting: Department of Ophthalmology, University of Vienna, Austria. Methods: In this prospective, double‐blind clinical trial, 36 patients had bilateral cataract surgeries performed from 1 to 3 months apart. Half of the patients had topical anesthesia for the first surgery and peribulbar anesthesia for the second surgery. The other half had peribulbar first and then topical. All surgery was done using a temporal clear corneal approach and bimanual phacoemulsification followed by in‐the‐bag intraocular lens implantation. Subjective pain was assessed using a visual analog scale of no pain (0%) to worst pain imaginable (100%) and intraoperative motility using a rank scale of adverse motility (−5) to ideal patient cooperation (+5). Results: Subjective pain was comparable whether topical or peribulbar anesthesia was used (mean 10.75 versus 10.97%; P > .6). Patient cooperation (motility) was significantly better when topical anesthesia was used (+2.16 versus +1.11; P = .03). There were no significant differences in complications. A peribulbar block was given in addition to the topical anesthesia in two cases. Conclusions: Topical anesthesia is a safe, effective alternative to peribulbar anesthesia in clear corneal cataract surgery.

Contrast sensitivity and glare disability with diffractive and refractive multifocal intraocular lenses

Purpose: To compare contrast sensitivity and glare disability provided by diffractive and refractive multifocal intraocular lenses (IOLs). Setting: University Eye Clinic Vienna, Austria. Method: This study evaluated the contrast sensitivity and glare disability in 29 eyes with a diffractive multifocal IOL (3M815LE) and 12 with a three‐piece, five‐zone refractive multifocal IOL (AMC Array SSM 26 NB). The Brightness Acuity Tester (Mentor, Inc.) was used with stationary sinusoidal gratings at spatial frequencies of 0.5, 1, 3, 6, 11.4, and 22.8 cycles per degree (cpd) generated on a television monitor (Nicolet CS 2000). Results: The contrast sensitivity functions of both multifocal IOL groups were within the reference range and were identical at 0.5, 1, and 22.8 cpd spatial frequencies. At 3, 6, and 11.4 cpd, the contrast sensitivity function in the diffractive IOL group was 6, 9, and 10% lower than in the refractive IOL group, and the difference between groups was statistically significant at 6 cpd. When glare was present, contrast sensitivity in the diffractive IOL group was generally in the lower limit of the reference range and remained below at 3 and 6 cpd. Contrast sensitivity in the refractive IOL group remained below the reference range at 3 cpd. At 0.5 and 1 cpd, there were no differences between the groups. At the middle and high spatial frequencies (3, 6, 11.4, 22.8 cpd), contrast sensitivity in the diffractive group was 8, 16, 11, and 12% lower than in the refractive group. At 6 cpd, the between‐group difference was statistically significant. Conclusion: Diffractive multifocal IOLs provided decreased contrast sensitivity and greater glare disability than refractive multifocal IOLs.

Long-term course of induced astigmatism after clear corneal incision cataract surgery

Purpose: To determine whether a small clear corneal temporal incision produces less surgically induced astigmatism than a larger incision. Methods: One hundred three consecutive cases of postoperative astigmatism after clear corneal incision cataract surgery were studied for a minimum of 1 year. Only self‐sealing incisions from the temporal side were made as follows: 3.2 mm (Group A); 4.0 mm (Group B); 5.2 mm (Group C). We considered the amount and axes of the keratometric readings at different times as well as their course over time. Induced astigmatism was calculated using three methods. Axial changes were also analyzed. Results: Immediately after the surgery, there was a small, surgically induced, withthe‐rule astigmatic shift in all groups, which in most cases decreased to near preoperative levels with time. One year postoperatively, mean induced astigmatism was 0.09 diopter (D) in Group A, 0.26 D in Group B, and 0.54 D in Group C. Most cases had minimal axial changes. In Group A, 86% had an axial change of fewer than 30 degrees; in Group B, 76%; and in Group C, 73%. Conclusion: The smallest incision group had the least surgically induced astigmatism and axial change. All incision groups remained stable and had satisfactory clinical results.

Visual properties of the foldable Array multifocal intraocular lens

Purpose: To evaluate visual acuity, depth of focus, contrast sensitivity, and glare disability in eyes with an Array SSM 26‐NB three‐piece, five‐zone multifocal intraocular lens (IOL). Setting: University Eye Clinic, Vienna, Austria. Method: Fourteen eyes with an AMO Array IOL were evaluated for uncorrected and best corrected distance and near visual acuity. The reading distance produced by the near focus of the lens was varied with convex glasses of less power. Reading at distance focus was evaluated by adding +3.50 diopters (D) to the distance correction. Depth of focus was measured from ‐3.00 to +6.00 D. Contrast sensitivity and glare disability were also measured using the Brightness Acuity Tester with stationary sinusoidal gratings at 0.5, 1, 3, 6, 11.4, and 22.8 cycles/degree. Results: Mean uncorrected distance acuity (Snellen) was 0.79 ± 0.17 (SD), which increased to 0.94 ± 0.14 with best correction. Near acuity was J2.75 ± 1.35 and J2.59 ± 1.10, respectively. When near focus was tested for reading distance, a mean of +0.54 ± 0.02 D was accepted for improvement of near vision of J1.71 ± 0.94. Near acuity with a distance focus addition of +3.50 D was J1.08 ± 0.28. Contrast sensitivity and glare disability were lower than in 13 eyes with a monofocal poly(methyl methacrylate) IOL and 16 normal phakic eyes. Conclusions: Eyes with the Array IOL had full distance function. Reading performance could be improved with a near focus of more than +3.50 D. Full near vision could be achieved with the distance focus and conventional reading glasses. Depth of focus was sufficient but visual acuity was limited at intermediate and near distance. Although contrast sensitivity was relatively low, it was not beyond the reference range.

Reading performance depending on the type of cataract and its predictability on the visual outcome.

Purpose: To investigate the influence of various types of cataract on reading performance in a standardized reading test setting. Setting: Department of Ophthalmology, University of Vienna, Vienna, Austria. Methods: The reading performance of 94 eyes with age‐related cataract and normal macular function was evaluated with the Radner Reading Charts preoperatively and 4 weeks after cataract surgery. Distance visual acuity was tested with the ETDRS charts. Cataracts were graded using the Lens Opacities Classification System (LOCS) III, on which NO is nuclear opalescence and NC is nuclear color. Results: Patients with pure nuclear cataracts (LOCS III: NO/NC 2.1‐5) achieved a normally high MRS (99.84% ± 7.65% of their postoperative MRS): preoperative MRS1: 190.6 ± 30.74 words per minute (wpm); postoperative MRS2: 191.21 ± 29.36 wpm. Patients with mixed nuclear‐cortical cataracts (LOCS III: NO/NC 2.1‐5; C>2) preoperatively achieved 96.96% ± 5.6% of their postoperative MRS (MRS1: 175.77 ± 31.54 wpm; MRS2: 181.34 ± 30.56 wpm). In dense nuclear cataracts (LOCS III: NO/NC>5), the MRS was significantly reduced, achieving only 72.64 ± 19.19% of the postoperative MRS (MRS1: 133.06 ± 39.43 wpm; MRS2: 185.76 ± 40.18 wpm). In posterior subcapsular cataracts, the preoperative MRS (134.1 ± 33.72 wpm) was significantly lower than postoperatively (191.14 ± 27.08 wpm). Conclusions: In contrast to dense nuclear cataracts and posterior subcapsular cataracts, the preoperative reading speed of patients with pure nuclear or nuclear‐cortical cataracts was normal at large print sizes. The preoperative evaluation of reading acuity and speed with standardized reading tests can therefore be used to estimate the postoperative reading performance in the latter 2 types of cataract.

Comparison of pseudoaccommodation and visual quality between a diffractive and refractive multifocal intraocular lens

Purpose: To determine depth of focus and visual quality after implantation of a diffractive intraocular lens (IOL) and a refractive IOL. Setting: University Eye Clinic, Vienna, Austria. Method: This study comprised 10 eyes of 9 patients with a diffractive IOL (3M 825x +4) and 13 eyes of 9 patients with a refractive lens (AMO Array SSM 26NB). Depth of focus was evaluated in a defocused range of −6.0 to +3.0 diopters (D), and Snellen visual acuity was recorded. Results: Distance acuity peaked at 1.0 ± 0.2 (3M group) and 0.91 ± 0.13 (AMO group). The near acuity peaks were at 0.82 ± 0.15 and 0.55 ± 0.14, respectively. Visual acuity of 0.5 was possible in a range of defocus of +1.0 to −4.0 D (3M) and +1.0 to −3.5 D (AMO). Conclusion: Pseudoaccommodation and full distance visual acuity were realized with both types of multifocal lenses. For intermediate distances, visual acuity may be limited to activities that do not require optimal vision. At near distances, the 3M lens provided statistically significantly better visual acuity.

Different techniques of extracapsular cataract extraction: bacterial contamination during surgery

This study was performed to investigate the correlation between the contamination of the anterior chamber and the technique of extracapsular cataract extraction (ECCE). Three different methods were used: uncomplicated planned ECCE, phacoemulsification involving suturing method, and sutureless technique. All patients had posterior chamber intraocular lenses implanted. Two hundred and thirty consecutive patients were included in this prospective study, and preoperative smears of the conjunctiva and intraoperative aspirates of the anterior chamber were investigated. Samples of the aqueous humor were taken at the beginning and at the end of the operation. Cultures were incubated and held for 14 days. More than 71% of the preoperative smears were contaminated by coagulase-negative staphylococci, the most commonly isolated bacteria. However, 27% of the patients had culture-positive anterior chamber aspirates intraoperatively, also with coagulase-negative staphylococci as the most frequent organisms. In no case did postoperative endophthalmitis develop. Preliminary results in a small population show that the contamination of the aqueous humor is statistically significantly less frequent if the cataract extraction is performed by phacoemulsification than if it is done without phacoemulsification. Another interesting finding is that anterior chamber contamination is not significantly more frequent, if a sutureless technique is used for cataract surgery.

Effect of levodopa on the human pattern electroretinogram and pattern visual evoked potentials

Pattern electroretinograms (P-ERGs) and pattern visual evoked potentials (P-VEPs) were recorded at three luminance levels and five different check sizes in a group of 16 control subjects before and after the oral administration of levodopa. At the lower luminance levels, significant decrease in P-ERG and P-VEP latencies were found. For P-VEPs the latency changes occurred only at small check sizes. No changes were observed in control experiments without levodopa administration. Our results show that levodopa-induced changes even occur at the retinal level and support a dopaminergic involvement in light and dark adaptation. Our observations are in agreement with a VEP delay found in Parkinsons disease and with a VEP latency increase in rats after dopamine depletion.

Comparison of contrast sensitivity between posterior chamber lenses of silicone and PMMA material

Seventeen patients received a posterior chamber lens of PMMA in one eye and a silicone lens (Staar Surgical Co.) in the other. Contrast sensitivity was examined in both eyes in order to detect differences with respect to the material used for lens implantation. An attempt was made to exclude any changes in the eyes that were not due to lens implantation and that might possibly have an influence on the result. A pairedT-test was performed for each spatial frequency. No statistically significant difference was found between the two materials with regard to contrast sensitivity.