Ординатура / Офтальмология / Английские материалы / Modern Cataract Surgery_Kohnen_2002

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Fig. 2. Cumulative distribution of uncorrected and corrected distance vision at 1 year (from Steinert et al. [3]).

in comparison to subjects implanted bilaterally with a PhacoFlex II SI40NB monofocal IOL (n 118). This prospective, randomized, double-masked, clinical trial was conducted at eight sites in the USA, seven sites in Germany, and one site in Austria. They reported mean uncorrected distance visual acuities of 20/21 (Snellen equivalent) in the subjects implanted with the multifocal IOL and 20/22 in subjects implanted with the monofocal IOL (p 0.05). Bestcorrected distance visual acuities were 20/18 in both groups (p NS).

Javitt et al. [11] reported on the results of the seven clinical sites in Germany and one site in Austria in the above trial, in which 64 subjects were implanted with the Array and 60 with the PhacoFlex II model SI40NB monofocal IOL. They reported mean uncorrected binocular distance visual acuities of 20/21 (multifocal) and 20/22 (monofocal) (p NS). Best-corrected binocular distance visual acuities were 20/18 and 20/17, respectively (p NS). Lesueur et al. [18] found both the Array SA40N with the P359 TUV PMMA bifocal IOL (Bausch & Lomb) to have similar mean corrected distance visual acuities (0.6).

Arens et al. [6] retrospectively evaluated binocular function after bilateral implantation of the Array multifocal (n 21) or a monofocal IOL (n 15). With distance correction, distance visual acuities were similar in multifocal and monofocal subjects for monocular and binocular vision. Without distance correction, distance acuity was significantly higher in the multifocal subjects for monocular vision. The monocular distance visual acuity was 0.53 0.19 for the Array multifocal lens and 0.41 0.27 for the monofocal lens (p 0.05). The

difference between binocular acuities was not significant. The authors suggested that this significant monocular difference may have been due to the intended visual outcome of myopia for the monofocal subjects and emmetropia for the multifocal subjects. Thus, the multifocal IOL caused no decrease in best-corrected distance acuity compared to the monofocal IOL, either monocularly or binocularly.

Vaquero-Ruano et al. [7] reported no difference in mean distance vision between the Array multifocal (n 50) and PMMA monofocal IOLs (n 50). Kamath et al. [25] studied interesting subjects with cataract and concurrent eye diseases (e.g., macular degeneration, glaucoma, diabetic retinopathy). They found the Array multifocal IOL produced distance visual outcomes comparable to those of the PhacoFlex SI40NB silicone monofocal IOL. They concluded that these subjects benefited from the multifocality and that management of their eye diseases was not compromised by the nature of the IOL.

Pieh et al. [15] found comparable distance visual acuity for the Array refractive multifocal IOL and the 3M 815LE diffractive bifocal IOL. The mean uncorrected distance acuity was 0.79 (Snellen decimal) with the refractive IOL and 0.61 with the diffractive. With best correction, mean distance visual acuity improved to 0.95 (refractive) and 0.96 (diffractive). Similarly, Liekfeld et al. [14] found no differences in distance visual acuity between the Array and the CeeOn 811E diffractive bifocal. Avitabile et al. [19] evaluated unilaterally implanted CeeOn 811E diffractive IOLs and found the mean uncorrected distance visual acuity to be 0.79 and mean corrected visual acuity 1.0.

Allen et al. [23] compared a Pharmacia diffractive bifocal IOL, model 808X (n 79), with a comparable monofocal (n 70) of the same design without the diffractive microstructure superimposed on the posterior surface. All subjects achieved a best-corrected visual acuity of 0.5 or better. Eighty percent of the monofocal and 71% of bifocal subjects achieved best-corrected visual acuity of 1.0 or better. Knorz et al. [5] reported the findings of a small study of 44 patients. Eleven patients had a True Vista bifocal implanted in one eye and a monofocal AMO PC 65CNB (Allergan Surgical) in the fellow eye (bifocalmonofocal subset). Corrected distance acuity was not significantly different between the two eyes. Uncorrected distance acuity was significantly better in the True Vista eyes, but this may have been the result of the study design, in which the goal was to have some with-the-rule astigmatism in the monofocal eyes but emmetropia in the True Vista eyes.

Knorz [20] reported the results of a European multicenter study of the True Vista bifocal IOL. Best-corrected distance acuity was 20/40 (Snellen) or better in 94% (259 of 275) at 4–6 months and 97% (185 of 191) at 7–11 months.

In summary, the refractive multifocal IOLs, refractive bifocal IOL, and several diffractive bifocal IOLs provided distance vision comparable to monofocal IOLs.

Fig. 3. Cumulative distribution of uncorrected and corrected near vision at 1 year (from Steinert et al. [3]).

Near Visual Acuity

The Array multifocal IOL offered significantly better near visual acuity than the monofocal IOLs in several clinical studies. In the multifocal-monofocal subset of the Steinert et al. [3] study, mean uncorrected near acuities were 20/33 for eyes implanted with the Array multifocal IOL and 20/54 for eyes implanted with the SI40NB monofocal IOL at 1 year after surgery, with a mean difference of two lines (p 0.0001). Uncorrected Jaeger (J) near visual acuity of J3 (20/40) or better was achieved by 86% (87 of 101) of eyes with the multifocal IOL, and by 49% (49 of 101) of eyes with the monofocal IOL (fig. 3). Uncorrected near visual acuity of J1 (20/20) or better was achieved by 47% (47 of 101) of eyes with the multifocal, and 12% (12 of 101) of eyes with the monofocal IOL. The distribution for near acuity with distance correction was similar to that for uncorrected near vision.

Javitt and Steinert [12] found statistically significant differences between subjects implanted with multifocal IOLs and those with monofocal IOLs. Mean uncorrected near visual acuities were 20/26 (Array multifocal) and 20/40 (SI40NB monofocal) (p 0.0001). Mean distance-corrected near visual acuities were 20/28 (multifocal) and 20/45 (monofocal) (p 0.0001).

Statistically significant differences in near visual acuities were reported by Javitt et al. [11]. In their study, mean uncorrected binocular near visual

acuities were 20/25 (multifocal) and 20/41 (monofocal) (p 0.001) and mean distance-corrected near visual acuities were 20/26 (multifocal) and 20/46 (monofocal) (p 0.001).

In subjects who had undergone extracapsular cataract extraction rather than phacoemulsification reported by Vaquero-Ruano et al. [7], eyes with the Array multifocal IOL had significantly better uncorrected and distance-corrected near acuities than eyes with a PMMA monofocal IOL (p 0.001). However, it is obvious that postoperative astigmatism is more easily controlled with phacoemulsification, and this is undoubtedly the preferred technique for multifocal surgeons. Lesueur et al. [18] found the mean distance-corrected near visual acuity in the P359 TUV PMMA bifocal group (n 22) to be significantly better than that of the Array SA40N group (n 24) (p 0.05).

A retrospective evaluation of binocular function by Arens et al. [6] showed that near visual acuity for both monocular and subjects with bilateral Array multifocal IOLs (n 21) was similar with or without distance correction. For subjects with bilateral monofocal (not identified) IOLs (n 5) near visual acuity was greater without correction than with correction for both monocular and binocular vision. Without distance correction there was no significant difference between near visual acuity for multifocal and monofocal subjects for monocular and binocular vision; however, monocular acuity was slightly lower than binocular. With distance correction, near acuity for multifocal subjects was significantly higher than that for monofocal subjects for both monocular (0.75 0.36 vs. 0.34 0.19; p 0.05) and binocular vision (0.91 0.31 vs. 0.52 0.21; p 0.05).

In contrast, Liekfeld et al. [14] found that near visual acuity and near visual acuity with distance correction was significantly better with the CeeOn 811E diffractive bifocal than the Array multifocal IOL at 4–6 weeks postoperatively (20/20 vs. 20/30) (p 0.002). The better near visual acuity for the CeeOn may be attributed, at least partially, to the higher magnification created by an add of 4 D, compared to an add of 3.5 D for the Array. However, the higher add theoretically reduces the working distance (depth of field) and creates a greater disparity between the in-focus image and the out-of-focus blur circle created by the alternate foci.

Avitabile et al. [19] found that 97% (34 of 35) of subjects with unilaterally implanted CeeOn 811E diffractive bifocals had uncorrected near visual acuity of J3 (20/40) or better. Also, Allen et al. [23] reported that the diffractive bifocal IOL, Pharmacia model 808X, performed better in tests of uncorrected near visual acuity and near acuity with distance correction than a comparable monofocal lens. Ninety-three percent of bifocal subjects could read J3 or better without correction and 99% with distance correction compared with 9 and 4%, respectively, for the monofocal IOL.

Knorz [20] reported best-corrected near acuity of 20/30 or better in 92% (250 of 272) of patients implanted with the True Vista IOL at 4–6 months postoperatively and in 87% (166 of 191) at 7–11 months. Knorz et al. [5] has also reported distance corrected near acuity was significantly better with the True Vista lens than the monofocal lens (p 0.007) in the bifocal-monofocal subset of their small study. Snellen near acuity with near add was significantly lower with the True Vista than the monofocal IOLs (p 0.008) but reading acuity was not significantly different.

In summary, the Array multifocal IOL offers significantly better near visual acuity than monofocal IOLs, as expected from the optical design. A new bifocal PMMA design from Bausch & Lomb showed good results in an early study, as did the 808X from Pharmacia. The refractive bifocal True Vista and diffractive bifocal CeeOn offer good near visual acuity.

Combined Distance and Near Visual Acuities

In the multifocal-monofocal subset of the study by Steinert et al. [3], 77% (78 of 101) of eyes implanted with the Array multifocal IOL achieved the combined distance (20/40 or better) and near visual acuity (J3 or better) criteria, compared to 46% of eyes implanted with the SI40NB monofocal IOL. With best distance correction, a significantly higher percentage of multifocal eyes achieved both these acuity levels compared to monofocal eyes (81 vs. 48%; p 0.0001). Thus, the Array multifocal IOL offers good acuity over a wider range of vision than a monofocal IOL.

Javitt and Steinert [12] reported that more subjects in the Array multifocal IOL group achieved combined distance and near visual acuities of 20/40 or better and J3 or better than those in the SI40NB monofocal IOL group (p 0.0001). These combined distance and near visual acuities were achieved by 96% (118 of 123) of subjects implanted with the multifocal and by 65% (71 of 109) of subjects implanted with the monofocal IOL.

Javitt et al. [11] reported that more subjects in the multifocal IOL group achieved both 0.5 (20/40) or better binocular distance visual acuity and J3 or better uncorrected binocular near visual acuity at the final postoperative exam than those in the monofocal IOL group (p 0.001). These were achieved by 97% (59 of 61) of subjects implanted with the multifocal and 66% (35 of 53) of subjects implanted with the monofocal IOL.

Depth of Focus

A major disadvantage of monofocal IOLs is that visual acuity is maximal at a distinct distance but then decreases with increasing defocus. In contrast, multifocal IOLs were designed to provide a wider range of visual acuity because of their multiple foci.

In the sub-study analysis by Steinert et al. [3], the Array multifocal IOL had a significantly greater depth of focus compared to the SI40NB monofocal (p 0.008) that was more pronounced in the near region, where a visual increase of approximately three lines occurred.

Vaquero-Ruano et al. [7] demonstrated that the Array had a significantly broader depth of focus than the monofocal, especially in the near vision range from 1 to 3 D (p 0.001). This is in agreement with Arens et al. [6] who found that subjects with bilateral Array multifocal IOLs (n 21) had a significantly wider range of focus in the near region than subjects with bilateral monofocal (not identified) IOLs (n 15) (p 0.05). Furthermore, these subjects had a greater total range than the monofocal subjects for a visual acuity threshold of 0.5 ( 1.0 to 3.0 D vs. 1.0 to 1.0 D). The multifocal and monofocal IOLs provided almost identical depth of focus around emmetropia.

The publication by Weghaupt et al. [17] showed that both the Array refractive multifocal and the 3M 825X diffractive multifocal IOL offer considerable depth of focus. The distance acuity peaks for the Array and the diffractive 825X were at Snellen decimal equivalents of 0.91 and 1.0, respectively; near acuity peaks were at 0.55 and 0.82, respectively. The diffractive IOL had statistically significant higher levels of visual acuity than the refractive IOL only in the defocused range of 2.5 to 4.0 D, consistent with the higher add for near in the diffractive compared to the refractive IOL ( 4.0 vs. 3.5 D). Visual acuity for both of these lens types was lowest in the intermediate range, with a shallow dip to 0.43 (Snellen decimal) at 2.0 D for the refractive and 0.42 at 1.5 D for the diffractive. Except for these dips, visual acuity of 0.5 or better was achieved with the refractive in the range of 1.0 to 3.5 D, and with the diffractive in the1.0 to 4.0 D range.

In a technically interesting paper, Ravalico et al. [13] examined range of vision by using high-pass resolution perimetry to assess the spatial resolution threshold in the central visual field of subjects implanted with either the refractive Array, refractive Domilens Progress 1, diffractive bifocal 811X (early model of CeeOn 811, Pharmacia Upjohn), or PMMA monofocal IOL. Each IOL type was implanted in 20 subjects. For distance vision, no significant differences were found between subjects with refractive multifocal IOLs or with monofocal IOLs, but subjects with the diffractive bifocal had a significantly higher (i.e., worse) spatial resolution threshold (p 0.003). For intermediate vision, the Array had a significantly lower (i.e., better) threshold compared to the other IOLs (p 0.01). The refractive Domilens Progress 1 was comparable to the monofocal for intermediate and near vision (p NS). For near vision, the diffractive bifocal 811X had better spatial resolution than any of the other IOLs (p 0.001); while the refractive monofocal Array performed better than either the refractive Domilens Progress 1 or the PMMA monofocal (p 0.001).

In summary, the Array multifocal IOL had a greater depth of focus than monofocal IOLs in the near vision range. Both refractive and diffractive multifocal IOLs can provide considerable depth of focus and performance over a range of distances.

Contrast Sensitivity

The greater depth of focus for a multifocal IOL compared to a monofocal IOL (discussed above) is a tradeoff for the decreased image clarity that results from multifocal vision. Because multifocal optics distribute incoming light through several foci, out-of-focus images are generated that overlap the image of a distant focus thereby reducing image clarity, particularly at low contrast levels.

In 43 of 67 subjects from the sub-study analysis by Steinert et al. [3], the Array IOL had significantly lower visual acuity than the SI40NB monofocal IOL at low contrast levels; however, there were no perceived disadvantages in visual function or subject satisfaction associated with this reduction. In return for the improved range of near and functional vision, subjects were apparently willing to accept the decrease in low contrast acuity.

The study by Lesueur et al. [18] included two measures of contrast sensitivity, the CSV 1000 (Vector Vision) with 4 spatial frequencies and 8 different contrasts, and the Gradual (Opsia) with letters at variable contrasts and 3 levels of luminance. They reported better contrast sensitivity with the investigational P359 IOL (p 0.001 with both tests). Vaquero-Ruano et al. [7] also reported significantly lower mean values of contrast sensitivity in the Array multifocal group compared to the PMMA monofocal group at low contrasts of 25 and 11% (p 0.001).

Arens et al. [6] reported no significant differences in best-corrected distance visual acuities between subjects with bilateral Array multifocal IOLs (n 21) and subjects with bilateral monofocal (unidentified) IOLs (n 15), either monocularly or binocularly, at contrast levels of 96, 50, or 25% (Regan Low Contrast Acuity Charts). At low contrast levels of 11%, however, the multifocal subjects had significantly lower sensitivity than the monofocal subjects for monocular vision (0.33 vs. 0.41, p 0.05). Acuities for binocular vision at the 11% contrast level were 0.40 in the multifocal group and 0.47 in monofocal group, which were not significantly different. The authors speculated that neural summation of the two monocular responses might be responsible for the higher sensitivity observed at the low contrast level for binocular compared to monocular vision.

Pieh et al. [15] compared contrast sensitivity and glare disability for the Array multifocal IOL (n 12) and the 3M 815LE diffractive bifocal IOL (n 29). A Brightness Activity Tester was used with stationary sinusoidal gratings at various spatial frequencies. At the lowest spatial frequencies

(0.5, 1 cycles per degree) and at the highest (22.8 cycles per degree) there was no difference between groups. At 3, 6 and 11.4 cycles per degree, the diffractive bifocal reached 90–94% of the contrast sensitivity function of the Array multifocal; the difference was significant at 6 cycles per degree (p 0.05). The slightly reduced contrast sensitivity for the diffractive bifocal compared to the Array refractive multifocal may be attributable to the different distributions of light for diffractive vs. refractive optics.

Both Allen et al. [23] and Haaskjold et al. [24] compared contrast sensitivity of the Pharmacia 808X diffractive bifocal IOL to that of a monofocal IOL. Allen’s group reported that contrast sensitivity was lower with the bifocal IOL than the monofocal IOL in medium light, but the mean values in each group remained within the normal range at each of five frequencies tested. Haaskjold’s group also reported lower contrast sensitivity with the diffractive bifocal than the monofocal IOL.

In the 11 patients with a True Vista IOL in one eye and monofocal in the fellow eye, Knorz et al. [5] found that, for both IOLs, contrast acuity values at far focus decreased with increasing pupil size. At high contrast (96%, 50%) with a dilated pupil, contrast acuity was similar for the True Vista and monofocal IOLs (p NS). At low contrast (50%, 25%, 11%) with a dilated pupil, the differences were significant in favor of the monofocal lens (p 0.07). It was also Knorz [20] who evaluated contrast acuity in a subgroup of best-case subjects in his larger study of 446 subjects. Subjects were evaluated in dim and bright light using the Regan Low Contrast Acuity Charts (96, 50, 25 and 11%). Contrast acuity with True Vista was comparable to that of the monofocal IOL for distance vision at 96, 50 and 25% contrast levels and was less than the monofocal IOL at 11% contrast level. Contrast acuity with True Vista was lower at near focus than at distance focus at all contrast steps tested and contrast acuity values at near focus were lower in bright light than in dim light. Knorz attributed the loss of contrast acuity in bright light to the smaller pupil size, which exposes a smaller area of the near annulus.

In summary, the main drawback of a multifocal IOL is loss of contrast at low contrast levels that results from the distribution of incoming light to several foci. This problem was greater with diffractive than refractive IOLs. In clinical practice, it is almost unheard of for a subject with an Array IOL to notice the reduced contrast sensitivity which, although measurable, seems to be at a subclinical level.

Visual Symptoms

Steinert et al. [3] collected data on visual symptoms from study subjects by means of a questionnaire. Subjects were asked to report their experience with glare/flare, halos, night vision, blurred near vision, distorted near vision, blurred