Potential Acuity Meter Research Articles

Comparison of distance and near visual acuity in patients with vision loss due to cataract.

The purpose of this study was to assess whether there is a disparity in distance and near best-corrected visual acuity (BCVA) in cataract eyes. 102 patients with cataract (N=121 eyes) were seen in clinic between January and November 2013 at the Wilmer Eye Institute Comprehensive Eye Service. An age-related macular degeneration (ARMD) group (N=27 eyes) was also identified for comparison. Distance and near BCVA were measured as part of the standard ophthalmic evaluation. Snellen measurements were converted to their LogMAR equivalents for statistical analysis. Near was better than distance BCVA with mean difference of 1.38 lines (P<0.001) in the cataract eyes. This disparity was not seen in the ARMD eyes. Near-distance BCVA disparity is a statistically significant finding seen with cataracts. This may have further implications in patients with both cataract and ARMD as the presence of disparity may suggest a cataract etiology playing a greater role in vision loss. This comparison may be useful for surgical prognostication and as a quick triage tool in conjunction with, or in place of, a potential acuity meter and dilated near-pinhole test.

Predicting postoperative visual outcomes in cataract patients with maculopathy.

Purpose:To assess the accuracy of the potential acuity meter (PAM) in predicting postcataract surgery visual acuity outcome in patients with healed inactive maculopathies.Study Design:Prospective interventional clinical trial.Patients and Methods:Patients scheduled for phacoemulsification had preoperative and 1 month postoperative best-corrected visual acuity (BCVA), PAM test, fluorescein angiography, and macular optical coherence tomography. Patients were grouped to following preoperative BCVA: PRE1: 0.29 and better, PRE2: 0.25–0.13, and PRE3: 0.1 or worse; age: G1 <60, G2 = 60–70, and G3 >70 years. PAM accuracy was divided into: Grade 1: Postoperative BCVA ≤1 or less line error of the PAM score, Grade 2: Between 1 and 2 lines error, and Grade 3: ≥3 lines or more error.Results:This study enrolled 57 patients with a mean age of 71.05 ± 6.78 years where 34 were females. There were 21 (36.84%) patients with diabetic maculopathy and 36 (63.16%) with age-related macular degeneration. The mean preoperative BCVA was 0.198 ± 0.12 (0.1–0.5). The mean PAM score was 0.442 ± 0.24 (0.1–1.3). The mean postoperative BCVA was 0.4352 ± 0.19 (0.17–1.00). The PAM score was in Grade 1, 2, and 3 in 46 (80.7%), 54 (94.7%), and 56 (98.2), respectively. There was a highly significant correlation between the PAM score and the postoperative BCVA (P < 0.001, Chi-square test). There was no correlation between the PAM test accuracy and age, gender, diagnosis, and preoperative BCVA (P = 0.661, 0.667, 0. 0.991, 0.833, Chi-square test; respectively).Conclusion:The PAM is an accurate method of predicting postoperative visual acuity for eyes with nuclear cataracts Grade I and II and inactive maculopathies.

Clinician versus potential acuity test predictions of visual outcome after cataract surgery

Background The aim of this study was to compare the ability of potential vision tests and clinical judgement to predict postoperative visual acuity after uneventful cataract surgery. Methods Sixty-two subjects (median, 74.5 years) were included in the study. Preoperative measurements included a clinical judgement prediction (based on case history and ocular examination alone), 2 super-illuminated pinhole techniques (distance and near), Potential Acuity Meter and interferometer. Postoperative visual acuity was used as the outcome measure to evaluate the accuracy of the preoperative predictions. Results Subjects were categorized as follows: (a) moderate cataract (N = 25); (b) moderate cataract and comorbidity (N = 18), and (c) advanced cataract (N = 19). Preoperative predictions within 2 lines of the postoperative visual acuity were as follows (a, b, and c respectively): clinical judgement (92%, 72%, 58%), super-illuminated pinhole distance (96%, 100%, 21%), super-illuminated pinhole near (92%, 78%, 26%), Potential Acuity Meter (72%, 67%, 21%), and interferometer (56%, 61%, 37%). Conclusions Based on the preoperative predictions above, none of the potential vision tests was useful compared with the clinical judgement in the advanced cataract group. The super-illuminated pinhole (distance) provided additional information beyond clinical judgement in the moderate cataract subgroup. The Potential Acuity Meter and interferometer were inaccurate even in the presence of moderate cataract, and this and other recent findings suggest they should no longer be considered adequate for potential vision assessment.

Fidelidade do "potential acuity meter" (PAM) no prognóstico da acuidade visual pós-operatória de cirurgia de catarata

To evaluate the correlation between the preoperative visual acuity (VA) obtained by the potential acuity meter (PAM) and the postoperative VA in a patient submitted to cataract surgery, as well as its correlation with the dominant morphologic classification of the cataract. This is a prospective study performed at the Hospital Monumento Study Center. Sixty-three eyes of 45 patients submitted to phacoemulsification with intraocular lens implantation were enrolled in this study and 1 eye had been excluded. Besides the complete examination in the preoperative period, PAM was used and its results were compared with the VA at the third postoperative month and correlated with the dominant morphologic cataract classification. The result was called satisfactory when the variation was equal to or less than two lines at the Snellen chart. We transformed the AV into logMAR for comparison with the literature. The mean age was 45.3 years with a mean VA of 0.64 logMAR by the PAM. At the third postoperative month, the mean best corrected visual acuity (BCVA) was 0.09 logMAR. The PAM overestimated the BCVA in 8 eyes (13%), underestimated it in 41 eyes (66%) and in 13 eyes (21%) the BCVA were the same. The satisfactory results regarding nuclear cataract were reduced in cases of higher density (1+/4 with 75.5% e 4+/4 with 33.3%) and increased in the posterior subcapsular cataracts (85.7%). PAM revealed an underestimation or maintenance of the BCVA in most cases (87%). Its fidelity was inversely proportional in the nuclear cataracts (1+/4 with 75.5% e 4+/4 with 33.3%) and higher in the posterior subcapsular cataracts.

Clinical study for postoperative visual acuity in cataract patients with the potential acuity meter

To study a new domestic potential acuity meter (PAM) for predicting visual acuity (PVA) in patients with cataracts and to compare the results to that measured by PAM-1000 and Lotmar. One hundred and fifty cataract eyes were enrolled in this study. PVA was evaluated with three different dioptometers before the surgery and compared to actual best corrected visual acuity (BCVA) obtained two months after the surgery. PVA obtained from domestic PAM correlated well with BCVA. In 56 eyes with non-identical results between PVA and BCVA, 52 eyes were false-negative and 3 eyes were false-positive, indicating that PAM tended to underestimate postoperative BCVA. In severe cataract patients, the correlation between PVA obtained from these three dioptometers and postoperative BCVA was decreased. The identical rates (as compared with postoperative BCVA) for the results obtained from PAM-1000 and Lotmar were 64. 0% and 62. 7%, respectively. Domestic PAM is relatively reliable for predicting postoperative visual acuity. It is a valuable method in the examination of PVA before the cataract surgery.

Capabilities of potential vision test measurements

To determine the usefulness of a battery of potential vision tests (PVTs) including potential acuity meter (PAM), laser interferometer (LI), critical flicker/fusion frequency (CFF), superilluminated pinhole at distance (SPH(d)) and near (SPH(n)), and optimal reading speed (ORS) by their independence of the effects of cataracts and sensitivity to macular disease (MD). Department of Optometry, University of Bradford, Bradford and Leeds General Infirmary, Leeds, United Kingdom. Potential vision test measurements were determined in 76 patients with age-related cataract and no other eye disease, 52 patients with MD and clear ocular media, and 28 patients with normal, healthy eyes. Potential vision tests were independent of the degrading effects of cataract up to a visual acuity (VA) level of 20/200 or worse (CFF), 20/125 (ORS and SPH), and 20/40 (PAM and LI). A high degree of association was found between PVT scores and distance VA in the MD group for SPH(d) (r2 = 0.93), SPH(n) (r2 = 0.89), and PAM (r2 = 0.71). A moderate correlation was found for LI (r2 = 0.55), CFF (r2 = 0.50), and ORS (r2 = 0.45). Potential acuity meter and LI showed very limited independence to moderate/dense cataracts and inaccurate predictions in patients with MD. Superilluminated pinhole was relatively unaffected by moderate/dense cataract and yet provided accurate predictions in the presence of MD and clear ocular media. Critical flicker/fusion frequency showed the greatest ability to bypass cataracts, although its ability to predict VA in patients with early MD was limited. The ORS was relatively unaffected by moderate/dense cataract, but its poor ability to predict VA in MD may limit its clinical suitability as a PVT.

Visual Performance of AcrySof ReSTOR Apodized Diffractive IOL: A Prospective Comparative Trial

Evaluate the visual performance of the AcrySof ReSTOR intraocular lens (IOL) and compare it with the monofocal SA60AT IOL. Prospective, nonrandomized, clinical trial. Forty patients (80 eyes) from the Federal University of São Paulo were enrolled in two groups. Twenty-five patients were assigned to the ReSTOR group and 15 patients to the monofocal group. Inclusion criteria were corneal astigmatism <1.0 diopter, potential acuity meter >0.2 logMAR units, and no associated ocular diseases. Parameters analyzed included distance uncorrected and best-corrected visual acuity, near uncorrected and distance corrected visual acuity, intermediate visual acuity, contrast sensitivity (Pelli-Robson chart), stereopsis (Titmus test), reading speed, wavefront measurement (LADARWave aberrometer), and a quality-of-life questionnaire. main outcome measure: Distance and near uncorrected and best distance corrected visual acuity, contrast sensitivity, and reading speed. Distance uncorrected and best-corrected visual acuity in the ReSTOR group were not statistically different from the monofocal group (P = .66). Near uncorrected and distance corrected visual acuity were statistically better in the ReSTOR group than the monofocal group (0.16 +/- 0.13 vs 0.62 +/- 0.09, P < .001, and 0.14 +/- 0.12 vs 0.62 +/- 0.07, P < .001, respectively). The ReSTOR group demonstrated less spherical aberrations compared with the monofocal group (P < .001). Monocular photopic contrast sensitivity was statistically lower in the ReSTOR group (P < .001). Stereopsis and reading speed were not statistically different between the groups. The AcrySof ReSTOR IOL provides a satisfactory full range of vision and achieves a more satisfactory quality of life when compared with the monofocal SA60AT IOL, but with lower contrast sensitivity.

Evaluation of the Potential Acuity Meter in Predicting Visual Acuity After Photodynamic Therapy for Choroidal Neovascularization

To evaluate the potential acuity meter in predicting visual acuity after photodynamic therapy of choroidal neovascular membranes caused by age-related macular degeneration. Retrospective study of 55 eyes in 51 patients with subfoveal predominantly classic choroidal neovascularization due to age-related macular degeneration. Pre-photodynamic therapy Snellen visual acuity minus the visual acuity with the potential acuity meter was compared with the actual improvement in visual acuity. Significant improvement in visual acuity after photodynamic therapy was defined as a gain of more than 2 lines in Snellen visual acuity (0.2 logarithm of the minimal angle of resolution units). Eighteen (51.4%) of 35 eyes with a potential for improvement experienced an actual improvement in their Snellen visual acuity after photodynamic therapy (P < .001). All eyes lacking a potential for improvement failed to experience an actual improvement in visual acuity after photodynamic therapy. The eyes that demonstrated better visual acuity with the potential acuity meter in this study seemed more likely to experience an improvement in visual acuity after photodynamic therapy.

Comparison of the potential acuity meter and the visometer in cataract patients

To compare the Guyton-Minkowski Potential Acuity Meter (PAM) and the Haag-Streit Lotmar Visometer (Visometer) in their ability to predict postoperative best corrected visual acuity (BCVA) in cataract surgery. University of British Columbia/Vancouver General Hospital Eye Care Center, Vancouver, British Columbia, Canada. In total, 292 eyes (223 patients) of subjects with cataracts and no known macular or optic nerve pathology were recruited over 6 months. Preoperative predictions of postoperative BCVA were compared with actual postoperative BCVA. The usefulness of these instruments as a 'diagnostic test' for predicting true surgical success (defined as postoperative BCVA of 20/40 or better) from predicted surgical success (PAM or Visometer predicted acuity 20/40 or better) was analysed. Neither the PAM nor the Visometer predictions were statistically significant predictors of postoperative BCVA. The sensitivities of PAM and Visometer for predicting surgical success were 84.7% and 96.1%, respectively. The specificity of the PAM and Visometer for predicting surgical success was 27.3% and 9.1%, respectively. Overall, 92.7% of patients had 'successful surgery'. Given a predicted success from the PAM or Visometer the post-test probability of success was 93.5% and 93.1%, respectively. Given a predicted failure from the PAM or Visometer there was a post-test probability of surgical success of 87.5% and 84.6%, respectively. We found no clinical benefit to support using the PAM or Visometer in the preoperative assessment of cataract patients with no known retinal or optic nerve pathology.

A comparison of the potential acuity meter (PAM) and the illuminated near card (INC) in patients undergoing phacoemulsification

To compare the accuracy of the potential acuity meter (PAM) and the illuminated near card (INC) in patients undergoing phacoemulsification. During presurgical evaluations, both PAM and INC were tested on each study patient following dilation. Patients then rated the subjective ease of use of each test. Best spectacle-corrected visual acuity (BSCVA) was recorded at 4 and 12 weeks postoperatively. McNemar's chi(2) test for paired associations was used to analyse categorical data; paired t-tests were used for continuous variables. Overall, the INC was more likely than the PAM to predict BSCVA within one Snellen line (P=0.002), but this difference decreased for accuracy within two lines. The PAM predicted BSCVA within one line in 87 (70.7%) eyes, as compared to 102 (82.9%) eyes by the INC. The PAM was accurate within two lines in 109 (88.6%) eyes; the INC was accurate in 115 (93.5%) eyes. The PAM was more likely to underpredict potential acuity (P<0.001), while the INC was more likely to overpredict (P=0.004) or give exact predictions of BSCVA (P<0.001). Accuracy of the INC declined in eyes with macular comorbidity. The PAM and INC were rated as 'easy' tests by 54 (45.4%) and 93 (78.2%) patients, respectively. Both the PAM and the INC were useful for predicting BSCVA after phacoemulsification, but the PAM was more likely to underestimate potential acuity. The INC was easier for patients to use, and had better accuracy than the PAM in patients without macular comorbidity, but was more likely to overestimate potential acuity.

Comparison of the potential acuity meter and pinhole tests in predicting postoperative visual acuity after cataract surgery

To compare the accuracy of potential acuity meter (PAM) and pinhole (PH) tests in predicting visual acuity after cataract surgery. Department of Ophthalmology and Visual Sciences, University of the Philippines, Philippine General Hospital, Manila, and Asian Eye Institute, Makati, Philippines. This prospective study comprised 64 eyes with mild to moderate cataract that had uneventful phacoemulsification. The PAM and PH tests were performed to predict postoperative visual acuity. Best corrected visual acuity (BCVA) 4 weeks after surgery was compared with the predicted visual acuity. The number of lines of inaccuracy was calculated by subtracting the BCVA from the predicted visual acuity. The variables analyzed were type of predictive test and preoperative BCVA. The eyes were divided according to preoperative BCVA as follows: Group 1, 20/20 to 20/50; Group 2, 20/60 to 20/100; Group 3, 20/200 or worse. The PH predicted visual acuity was correct in 5% of eyes and the PAM predicted acuity, in 17%. The PH predicted acuity was accurate within 1, 2, and 3 lines of BCVA in 23%, 40%, and 54% of eyes, respectively, and the PAM predicted acuity, in 64%, 81%, and 92% of eyes, respectively. The mean number of lines of inaccuracy was significantly less with the PH than with the PAM (3.47 lines +/- 2.42 [SD] and 1.60 +/- 1.55 lines, respectively) (P=.0005). The mean lines of inaccuracy in Group 1 were 2.49 +/- 1.52 for the PH and 1.14 +/- 0.99 for the PAM (P=.027); in Group 2, 3.17 +/- 1.99 PH and 1.65 +/- 1.80 PAM (P=.642); and in Group 3, 6.58 +/- 3.03 PH and 2.67 +/- 2.10 PAM (P=.240). The PAM was more accurate than the PH in predicting visual acuity after cataract surgery. The accuracy of both tests decreased in patients with poorer preoperative visual acuity.

Critical Flicker Frequency as a Potential Vision Technique in the Presence of Cataracts

Potential vision testing attempts to predict the visual outcome that might be expected as a result of a cataract operation. This report details the clinical utility of critical flicker frequency (CFF) as a potential vision test (PVT). CFF thresholds were determined in 31 subjects with age-related idiopathic cataract and no other eye disease, 19 subjects with macular disease (MD) and clear ocular media, and 24 age-matched control subjects. In addition, the CFF technique was administered before cataract surgery in 52 patients and compared with the information provided by presurgical case history and ocular examination alone (ophthalmological judgment [OJ]) and results from two commonly used PVTs (the retroilluminated pinhole and the potential acuity meter). CFF thresholds obtained in the nonsurgical cataract group were unrelated to cataract severity and were similar to those in the control group. In contrast, CFF scores were significantly related to visual acuity (VA) in the MD group. In the pre- and postsurgical studies, OJ predicted postoperative VA very well in patients with moderate cataract and normal fundi and better than all the PVTs. OJ performed less well in patients with comorbid eye disease and dense cataracts, when information from the PVTs would probably have been useful. CFF provided the most accurate predictions of postoperative VA in the small sample of patients with dense cataracts. CFF was unaffected by cataract, yet sensitive to MD, and provided useful information about the postoperative visual outcome beyond that obtained through history and ocular examination in patients with dense cataracts.

Rapid visual rehabilitation after endothelial transplants with deep lamellar endothelial keratoplasty (DLEK)

To evaluate the speed of visual recovery in 30 consecutive patients with Fuchs endothelial dystrophy who received deep lamellar endothelial keratoplasty (DLEK) transplant surgery.Best spectacle-corrected visual acuity (BSCVA) by manifest refraction and uncorrected visual acuity (UVA) were prospectively measured at preop, at 1 week, and at 1, 3, 6, 12, and 18 months after DLEK. The LogMAR of the postop vision was compared against each patient's preop vision. Visual results at 6 months were also compared against potential acuity meter (PAM) results in 27 patients. All eyes had reached at least the 6-month follow-up interval.Two of the first 32 eyes originally enrolled in the protocol were converted at surgery to standard penetrating keratoplasty (PK), and so DLEK data were obtained on 30 eyes for this report. Average BSCVA and UVA were better than preop vision at every time point, achieving statistical significance by 3 months (P < 0.05). Average preop BSCVA was 20/162 (range 20/40 to CF), improving to 20/63 at 3 months (range 20/25 to 20/200), 20/56 at 6 months, 20/51 at 1 year, and 20/46 at 18 months. Of the 27 patients who had PAM testing, 52% (14 of 27) had BSCVAs within 1 line of their PAM at 3 months, 63% (17 of 27) were within 1 line at 6 months, 71% (12 of 17) were within 1 line at 1 year, and 83% (10 of 12) were within 1 line at 18 months (P < 0.05 compared with preop from 3 months on).DLEK surgery preserves the normal corneal surface topography and allows rapid visual recovery of useful vision by 3 months. The visual acuity continues to improve over time.

Rapid visual rehabilitation after endothelial transplants with deep lamellar endothelial keratoplasty (DLEK).

To evaluate the speed of visual recovery in 30 consecutive patients with Fuchs endothelial dystrophy who received deep lamellar endothelial keratoplasty (DLEK) transplant surgery. Best spectacle-corrected visual acuity (BSCVA) by manifest refraction and uncorrected visual acuity (UVA) were prospectively measured at preop, at 1 week, and at 1, 3, 6, 12, and 18 months after DLEK. The LogMAR of the postop vision was compared against each patient's preop vision. Visual results at 6 months were also compared against potential acuity meter (PAM) results in 27 patients. All eyes had reached at least the 6-month follow-up interval. Two of the first 32 eyes originally enrolled in the protocol were converted at surgery to standard penetrating keratoplasty (PK), and so DLEK data were obtained on 30 eyes for this report. Average BSCVA and UVA were better than preop vision at every time point, achieving statistical significance by 3 months (P < 0.05). Average preop BSCVA was 20/162 (range 20/40 to CF), improving to 20/63 at 3 months (range 20/25 to 20/200), 20/56 at 6 months, 20/51 at 1 year, and 20/46 at 18 months. Of the 27 patients who had PAM testing, 52% (14 of 27) had BSCVAs within 1 line of their PAM at 3 months, 63% (17 of 27) were within 1 line at 6 months, 71% (12 of 17) were within 1 line at 1 year, and 83% (10 of 12) were within 1 line at 18 months (P < 0.05 compared with preop from 3 months on). DLEK surgery preserves the normal corneal surface topography and allows rapid visual recovery of useful vision by 3 months. The visual acuity continues to improve over time.

Ten-year follow-up of epikeratophakia for the correction of high myopia

Objective To determine the long-term functional results of epikeratophakia for myopic patients. Design Retrospective, noncomparative, interventional case series. Participants Twenty-two patients (32 eyes; average age, 43±6 years) who underwent epikeratophakia surgery for high myopia. Mean preoperative myopia was −18.74±9.16 diopters (D; range, −7 D to −49 D). Follow-up was 12±2 years. Main outcome measures Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), change in mean keratometry, visual acuity under glare conditions, BCVA versus potential acuity meter reading, and patient satisfaction with the visual outcome. Results Mean preoperative UCVA increased from 20/800±20/400 (range, counting fingers–20/400) to 20/80±20/200 (range, 20/250–20/32) in 24 eyes. Mean preoperative BCVA of 20/32±20/64 increased only in five eyes, whereas six eyes had no change and 18 eyes had a more than one line loss of Snellen BCVA. Mean preoperative keratometry reading decreased from 43.67±0.90 D (range, 41.0–46.25 D) to 37.40±2.92 D (range, 29.43–47.68 D). In the presence of glare, mean BCVA decreased to 20/100±20/100 (range, counting fingers–20/32). Potential acuity meter (PAM) readings were significantly ( P<0.05) higher than BCVA. Mean PAM reading was 20/25±20/100 (range, 20/100–20/16). Seven patients (11 eyes) were extremely satisfied with the operative result more than 10 years after the operation, whereas four patients (four eyes) were not satisfied at all. Conclusions Epikeratophakia for the correction of myopia improved UCVA significantly, but BCVA decreased. The removal of the lenticules in patients who were not satisfied with their visual acuity was uncomplicated, and acceptable vision could be achieved with either contact lenses or intraocular lens implantation.

Accuracy of IRAS GT interferometer and potential acuity meter prediction of visual acuity after phacoemulsification: Prospective comparative study

Purpose: To assess and compare the accuracy of 2 methods of predicting visual acuity after phacoemulsification. Setting: Department of Ophthalmology, Montpellier, France. Methods: This prospective study evaluated 47 eyes of 47 patients having uneventful phacoemulsification over a 1-month period. All the patients had mild to moderate cataract. Visual acuity recovery was predicted using the white-light IRAS GT® interferometer on the 3- and 8-degree wide test area and the Guyton-Minkowski potential acuity meter (PAM). Best corrected visual acuity was evaluated 1 day before and 1 month after surgery. Results: Both the interferometer and PAM underestimated the retinal visual capacity. Three-degree white-light interferometry gave significantly better mean predicted results than 8-degree interferometry and the PAM. There was no statistically significant disparity between predicted and postoperative results with 3-degree interferometry (1.04 ± 0.57 logMAR; −0.09 ± 0.27 decimal) ( P = .0647) and a statistically significant disparity with 8-degree interferometry (0.89 ± 0.59 logMAR; −0.13 ± 0.27 decimal) and the PAM (0.66 ± 0.62 logMAR; −0.22 ± 0.24 decimal) ( P = .0001). The predicted values were widely dispersed; the correlation indices were 0.38 with the PAM ( P = .091), 0.39 with 3-degree interferometry ( P = .001), and 0.49 with 8-degree interferometry ( P = .0005). Conclusions: Three-degree white-light interferometry gave more accurate results than 8-degree interferometry and the PAM. The wide dispersion of results and unsatisfactory correlation indices show the tests are poor predictors of individual acuity. They should be used semiquantitatively and the results interpreted in relation to the clinical data. Qualitative methods may be useful in confirming or refuting visual recovery capacity ascertained by quantitative systems.

Potential acuity meter results in cataract patients.

To determine the ability of the potential acuity meter (PAM) to predict potential visual acuity through lenticular opacities in a group of cataract patients without significant other ocular pathology. This prospective study undertook PAM measurements on each eye of 84 subjects during preoperative hospital visits to either A Scan or Primary Care clinics. PAM results were compared to best corrected visual acuity findings obtained at least 6 weeks post-cataract extraction. Comparison of PAM result to visual outcome showed poor correlation (rho = 0.41, P = 0.0005). Using predictive estimates, 49% of subjects' PAM results underestimated visual outcome as determined by a difference of greater than 2 Snellen acuity lines in these results. Factors such as preoperative vision level, cataract type and pupil dilation did not significantly influence the predictive power of the PAM. Preoperative pinhole results were also correlated with visual outcome (rho = 0.42, P = 0.0006). Vison in the fellow eye of subjects with 6/9 or better was correlated to the PAM result indicating a moderate to good predictive power in 'normal' eyes. PAM results were considered to be poor for a clinical test. The results of this study indicate that this instrument has only a limited usefulness as part of the standard preoperatve examination in patients undergoing cataract extraction.

Potential acuity meter accuracy in cataract patients

Purpose To determine potential acuity meter (PAM) accuracy in patients with cataract as the only ocular disease. Setting Hospital de Clínicas de Porto Alegre, Brazil. Methods This prospective study comprised 74 eyes with cataract. Patients with other ocular pathology diagnosed before or after surgery, as well as those with complicated surgeries, were excluded. All patients had PAM evaluation before surgery; these results were compared to the final postoperative visual acuity. Patients were divided into 4 cataract groups based on the Lens Opacity Classification System II: Group 1, early cataracts (nuclear opalescence [NO] 1 and/or posterior subcapsular cataracts [P] 1 and/or cortical opacity [C] < 2); Group 2, definite cataracts (NO2 and/or C2, with or without P1); Group 3, posterior cataracts (P2 or P3); Group 4, mature cataracts (N3 and/or C ≥ 3, with or without P1). The PAM result was considered accurate if it was within 2 lines of the postoperative best spectacle-corrected visual acuity (BSCVA) 3 months after surgery. Results All patients had a BSCVA of 20/20. Accuracy of the PAM was 58.3% in Group 1, 50.0% in Group 2, 27.8% in Group 3, and 6.7% in Group 4 ( P = .000 017). Patient age did not influence the results. Conclusions The PAM may be used as a complementary tool in evaluating early and nondense cataracts; however, patients should not be excluded as candidates for cataract surgery based solely on PAM results.

Perception of Purkinje vessel shadows and foveal granular pattern as a measure of potential visual acuity

PurposeTo compare perception of 2 entoptic phenomena, the Purkinje vessel shadows and the foveal granular pattern, as measures of retinal visual acuity using a transscleral illumination technique that bypasses the anterior segment. SettingRetinal Vascular Center and General Eye Clinic, Wilmer Ophthalmological Institute, Johns Hopkins Hospital, Baltimore, Maryland, USA. MethodsBoth eyes of 85 patients with clear ocular media, many with retinal disease, were tested for perception of these entoptic phenomena. Also, retinal visual acuity was measured with a Potential Acuity Meter through the current refractive correction. ResultsOf 114 eyes with retinal acuity of 20/40 or better, 99% perceived the Purkinje vessel shadows and 86% perceived the foveal granular pattern. Of 45 eyes with retinal acuity of 20/80 or worse, 73% perceived the Purkinje vessel shadows and 4% perceived the foveal granular pattern. ConclusionPerception of the Purkinje vessel shadows does not distinguish between good and poor retinal acuity, whereas nonperception of the vessel shadows strongly suggests poor acuity. Perception of the foveal granular pattern, on the other hand, provides a positive indication of good retinal acuity and will likely prove to be predictive of good vision after removal of significant media opacity.

Potential acuity pinhole: A simple method to measure potential visual acuity in patients with cataracts, comparison to potential acuity meter

ObjectiveTo describe the potential acuity pinhole (PAP) test and compare its accuracy to the potential acuity meter (PAM) in predicting visual outcome after cataract surgery. Study designProspective case series. ParticipantsA total of 56 preoperative patients with cataracts participated. Main outcome measuresAccuracy of predicting postoperative distance visual acuity was measured. MethodsLines of inaccuracy were calculated by subtracting actual postoperative best-corrected distance visual acuity (BCVA) from predicted values. Variables analyzed were method of prediction, preoperative BCVA, and preoperative spherical equivalent. ResultsThe PAP test predicted visual outcomes within 2 lines in 100%, 100%, and 56% of eyes with preoperative BCVA of 20/50 and better (group I), 20/60 to 20/100 (group II), and 20/200 and worse (group III), respectively. The PAM predictions within 2 lines for the same groups were 42%, 47%, and 0%, respectively. Mean lines of inaccuracy of PAP predictions were 0.83, 1.11, and 3.50 lines for groups I, II, and III, respectively. Mean lines of inaccuracy for PAM predictions were 2.50, 2.68, and 6.22 lines for the same groups. Differences in lines of prediction between PAM and PAP were 1.67 (P = 0.004), 1.58 (P = 0.0002), and 2.72 lines (P = 0.0001) for groups I, II, and III, respectively. There was no statistically significant correlation between PAP predictions and preoperative myopic spherical equivalent. ConclusionsThe PAP test is a simple, inexpensive, and relatively reliable method to estimate visual outcome after uncomplicated cataract surgery in eyes with no coexisting disease. It is less accurate in patients with preoperative BCVA worse than 20/200. It appears to be more predictive than PAM.