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References    Please note:  "Retinal Acuity Meter" (RAM) was formerly named the Illuminated Near Card (INC)

Pre RAM data (prior to 1990) did not support the usefulness of potential vision testing prior to cataract surgery

    Literature review. Ophthalmology 1993;100:150S-177S.

40 articles published between January 1, 1975-December 31, 1990 were reviewed and included the following instruments.not

   Potential Acuity Meter (PAM)

   Interferometers

Conclusions: Limited Usefulness
Overall, the reported studies did not provide enough evidence to support the use of potential vision testing to detect poor surgical outcomes.  If anything, they suggested that the utility of these tests was limited to cases in which the cataract was not dense.  In such situations, the ophthalmologist can usually visualize the fundus and determine from clinical examination whether cataract surgery is likely to improve vision.

What was learned for the publications and this review?

For a tester to be useful it must accurately predict poor surgical outcomes. 

        Therefore a tester must be accurate in eyes with co-morbid disease and not only in eyes with cataract alone. 

         Unfortunately many researchers failed to include cases with co-morbid diseases and therefore their results are clinically meaningless.

RAM data (1996 to present) does support the usefulness of the RAM for measuring retinal acuity to predict good and poor outcomes.

Summary of the Studies on potential vision testers since 1990

Code:

J: Accurately predicts in eyes with co-morbid diseases and cataract alone

L: Inaccurately predicts in eyes with co-morbid diseases or with cataract alone
        Less than 80% to within 2 Lines in eyes with pre-op better than 20/200

K?? : No co-morbid diseases in the study: A meaningless clinical study as per the 1993 review article.

In eyes with no co-morbid disease, there is no need for prediction because all will have good post-op outcomes.

        Useful = In eyes with cataract alone and in eyes with co-morbid disease the predictions are within 2 lines in at least 80% of patients when pre-op vision is better than 20/200.                      
 

A.  The History and Eye EXAM a predictor of potential vision (Useful: 0/1 study)

  L  del Romo, B.G., Douthwaite, W.A., and Elliott, D.A.: Critical flicker frequency as a potential vision technique in the presence of cataracts.  Investigative Ophthalmology and Visual Science 46:1107-12, 2005

Bevel: LinkCri
L  Asbell, P.A., Chiang, B., Amin, A, and Podos, S.M.:  Retinal acuity evaluation with the potential acuity meter in glaucoma patients. Ophthalmology 92:764-7, 1985.
tical Flicker Frequency as a Potential Vision Technique in the Presence of Cataracts -- Romo et al. 46 (3): 1107 -- Investigative Ophthalmology & Visual Science
Cataract Alone: Excellent Predictions (95%)
Co-Morbid Disease: Poor Predictions (50%Data Link

BPAM (Potential Acuity Meter) (Useful: 2/13 studies or 25% of users)

 L  Asbell, P.A., Chiang, B., Amin, A, and Podos, S.M.:  Retinal acuity evaluation with the potential acuity meter in glaucoma patients. Ophthalmology 92, 764-7, 1985.

Bevel: LinkCri
L  Asbell, P.A., Chiang, B., Amin, A, and Podos, S.M.:  Retinal acuity evaluation with the potential acuity meter in glaucoma patients. Ophthalmology 92:764-7, 1985.
tical Flicker Frequency as a Potential Vision Technique in the Presence of Cataracts -- Romo et al. 46 (3): 1107 -- Investigative Ophthalmology & Visual Science
Mild to Moderate Glaucoma: Excellent Predictions (91 to 100%)  Data Link
Severe Glaucoma: Poor Predictions (44%)


  L
  Stewart, W.C., Connor, A.B., and Hunt, H.H.:  Prediction of postoperative visual acuity in patients with total glaucomatous cupping using the potential acuity meter and automated perimetry.  Ophthalmic Surgery 24:730-4, 1993.

Bevel: LinkCri
L  Asbell, P.A., Chiang, B., Amin, A, and Podos, S.M.:  Retinal acuity evaluation with the potential acuity meter in glaucoma patients. Ophthalmology 92:764-7, 1985.
tical Flicker Frequency as a Potential Vision Technique in the Presence of Cataracts -- Romo et al. 46 (3): 1107 -- Investigative Ophthalmology & Visual Science
 Co-morbid Disease: Poor Predictions (50%Data Link

           J    Alio, JL, et. al:  Accuracy of the potential acuity meter in predicting the visual outcome in cases of cataract associated with macular degeneration. Eur. J Ophthalmology 3:189-92, 1993.

Bevel: LinkCri
L  Asbell, P.A., Chiang, B., Amin, A, and Podos, S.M.:  Retinal acuity evaluation with the potential acuity meter in glaucoma patients. Ophthalmology 92:764-7, 1985.
tical Flicker Frequency as a Potential Vision Technique in the Presence of Cataracts -- Romo et al. 46 (3): 1107 -- Investigative Ophthalmology & Visual Science
Cataract Alone: Excellent Predictions (r = 0.77)
Co-Morbid Disease: Excellent Predictions (r = 0.77 & r = 0.58)
 Data Link

K??   Tharp, A, Cantor, L, Yung, C, and Shoemaker, J.:  Prospective comparison of the Heine Retinometer with the Mentor Guyton-Minkowski potential acuity meter for assessment of potential visual acuity before cataract surgery.:  Ophthalmic Surgery 25: 576-9, 1994.

Cataract Alone: Poor Predictions (false-negatives rate = 44%) Data Link
            No Co-morbid diseases studied
 

L   Lasa, M.S., Datiles, M.B., and Feidlin, V.: Potential vision tests in patients with cataracts. Ophthalmology 102:1007-11, 1995.

Cataract Alone: Poor Predictions (74%)
Co-Morbid Disease: Poor Predictions (73%)
 Data

L   Asbell, P.A., Krashin-Bishler, I, Perez, V., Schechter, C. and So, P.: Scientific Poster #253, American Academy of Ophthalmology, 1996. 

Glaucoma: Poor agreement with distance acuity (42%) Data link

L   Cuzzani, O.E., Ellant, J.P., Young, P.W., Gembel, H.V., and Rydz, M.:  Potential acuity meter versus scanning laser ophthalmoscope to predict visual acuity in cataract patients.  J Cataract Refractive Surg 24:263-9, 1998.

Cataract Alone: Poor Predictions (50%)
Co-Morbid Disease: Poor Predictions (61%)
 Data Link

K?? Melki, S.A., Safar,  A., Martin, J., Ivanova, A., and Marwa, A.: Potential acuity pinhole. Ophthalmology 106, 1262-7, 1999.
            Cataract Alone: Poor Predictions (47%) Data Link
            No Co-morbid diseases studied
 

K??   Gus, P.I., Kwitko, I., Roehe, D., and Kwitko, S.:  Potential acuity meter accuracy in cataract patients.  J Cataract Refractive Surg 26:1238- 41, 2000.

Cataract Alone: Poor Predictions (58%) Data Link
            No Co-morbid diseases studied
 

K ??  Devereux, C. J., et. al: Potential acuity meter results in cataract patients. Clinical & Experimental Ophthalmology 28:414-8, 2000.

Cataract Alone: Poor Predictions (51%) Data Link
            No Co-morbid diseases studied
 


K ??      Le Sage, C., et. al: Accuracy of IRAS GT interferometer and potential acuity meter prediction of visual acuity after phacoemulsification-Prospective comparative study. J Cataract Refract Surg 28:131-8, 2002. 

Cataract Alone: Poor Predictions (r = 0.38)

L  del Romo, B.G., Douthwaite, W.A., and Elliott, D.A.: Critical flicker frequency as a potential vision technique in the presence of cataracts.  Investigative Ophthalmology and Visual Science 46:1107-12, 2005.

Cataract Alone: Poor Predictions (70%)
Co-Morbid Disease: Good Predictions (83%)
 Data Link

K ??   Uy, H.S. and Munoz, V.M.R.:  Comparision of the potential acuity meter and pinhole tests in  predicting postoperative visual acuity after cataract surgery. J Cataract Refractive Surg 31:548-52, 2005.

Cataract Alone: Good Predictions (81%) Data Link
            No Co-morbid diseases studied

J   Chang, MA, Airiani, S, Miele, D, Braunstein, RE : A Comparison of the Potential Acuity Meter (PAM) and the Illuminated Near Card (INC) in Patients undergoing Phacoemulsification.  EYE 2006) 20, 13451351.

Cataract Alone: Very Good Predictions (87%)
Co-Morbid Disease: Excellent Predictions (93%)
 Data Link

C.  Interferometry (Useful: 0/3 studies)

L    Lasa, M.S., Datiles, M.B., and Feidlin, V.: Potential vision tests in patients with cataracts. Ophthalmology 102:1007-11, 1995.

Cataract Alone: Excellent Predictions (94%)
Co-Morbid Disease: Poor Predictions (77%)
 Data Link

K ??   Le Sage, C., et. al: Accuracy of IRAS GT interferometer and potential acuity meter prediction of visual acuity after phacoemulsification-Prospective comparative study. J Cataract Refract Surg 28:131-8, 2002. 

Cataract Alone: Poor Predictions (r = .39) Data Link
           
No Co-morbid diseases studied

K ??   Tharp, A, Cantor, L, Yung, C, and Shoemaker, J.:  Prospective comparison of the Heine Retinometer with the Mentor Guyton-Minkowski potential acuity meter for assessment of potential visual acuity before cataract surgery.:  Ophthalmic Surgery 25: 576-9, 1994.

Cataract Alone: Poor Predictions (false-negatives rate = 32%) Data Link
           
No Co-morbid diseases studied

D.  RAM (Retinal Acuity Meter) (Useful: 6/6 studies)

J   Hofeldt, A.J.: Illuminated near card assessment of potential visual acuity. J Cataract Refract Surg. 22:367-371, 1996.

Capsule Alone: Excellent Predictions (100%)
Co-Morbid Disease: Excellent Predictions (100%)
 Data Link

J    Weiss, M.J. and Hofeldt, A.J.: Illuminated near card assessment of potential acuity in macular disease. Vitreous Society Meeting, 1996.

Co-Morbid Disease: Excellent Predictions (98%) Data Link

J    Asbell, P.A., Krashin-Bishler, I, Perez, V., Schechter, C. and So, P.: Scientific Poster #253, American Academy of Ophthalmology, 1996. 

Glaucoma: Excellent agreement with distance acuity (92%) Data Link

J   Hofeldt, A.J. and Weiss M.J.: The illuminated near card assessment of acuity in eyes with cataract. Ophthalmology 105, 1531-6, 1998. 

Cataract Alone: Excellent Predictions (97%)
Co-Morbid Disease: Excellent Predictions (100%)
 Data Link

J    Chang, MA, Airiani, S, Miele, D, Braunstein, RE : A Comparison of the Potential Acuity Meter (PAM) and the Illuminated Near Card (INC) in Patients undergoing        
            Phacoemulsification. 
EYE 2006) 20, 13451351.

Cataract Alone: Excellent Predictions (94%)
Co-Morbid Disease: Excellent Predictions (93%)
 Data LinkData Link

J Park, JI, Oh, SH, Kim, JH, Moon, SW, Lee, DH:  The Potential Role of the Retinal Acuity Meter For Predicting Visual Outcome after Cataract SurgeryJ Korean Ophthalmol
            Soc
. 2007 Jul;48(7):898-904

            Cataract Alone: Excellent Predictions (91.6%)*
           
Co-Morbid Disease: Excellent Predictions (90.9%)
Data Link

            *Prediction within 3 lines of letters

E.  SLO (Scanning Laser Ophthalmoscope) (Useful: 1/1 study)

J    Cuzzani, O.E., Ellant, J.P., Young, P.W., Gembel, H.V., and Rydz, M.:  Potential acuity meter versus scanning laser ophthalmoscope to predict visual acuity in cataract patients.  J Cataract Refractive Surg. 24: 263-9, 1998.

Cataract Alone: Very Good Predictions (88%)
Co-Morbid Disease: Excellent Predictions (100%) Data Link


F.  PAP (Potential Acuity Pinhole) (Useful 0/1
study)

KCataract Alone: Excellent Predictions (100%) Data Link
No Co-morbid diseases studied
 

G.  Pinhole at distance (1.5mm) Useful: 0/1 study)

K ??    Uy, H.S. and Munoz, V.M.R.:  Comparison of the potential acuity meter and pinhole tests in predicting postoperative visual acuity after cataract surgery. J Cataract Refractive Surg 31, 548-52, 2005

Cataract Alone: Poor Predictions (40%) Data Link
No Co-morbid diseases studied

 H.  SP (Super-Pinhole) (Useful 0/1 study)

L   del Romo, B.G., Douthwaite, W.A., and Elliott, D.A.: Critical flicker frequency as a potential vision technique in the presence of cataracts.  Investigative Ophthalmology and Visual Science 46:1107-12, 2005.

Cataract Alone: Poor Predictions (73%)
Co-Morbid Disease: Good Predictions (83%)
 Data Link

 I. VMF (Vryghem Macular Function) (Useful 0/1 study)

L  Vryghem, J.C., Cleynenbreugel, H.V., Van Calster, J., Leroux, K.: Predicting cataract surgery results using a macular function test.  J Cataract Refractive Surg. 30:2349-53, 2004.

Cataract Alone: Excellent Predictions (94%)*  Data Link
          
 Co-morbid Disease: 32%**

     * Positive predictive value

     ** Negative predictive value

Overestimation reported in several disease:

1. Amblyopia

2. Early stage macular degeneration

3. Macular pucker

4. Corneal scar

5. Undiagnosed conditions, 9 eyes.


             The system magnifies images 200% ( 8 diopter has 3X power at 12 cm)                         

 

J.  CFF (Critical Flicker Frequency) (Useful 0/1 study)

L    del Romo, D.G., Douthwaite, W.A., and Elliott, D.A.: Critical flicker frequency as a potential vision technique in the presence of cataracts.  Investigative Ophthalmology and Visual Science, 2005;46:1107-12.

Cataract Alone: Poor Predictions (77%)
Co-Morbid Disease: Poor Predictions (58%) Data Link

Home Doctors Comments Partial List of Users RAM User Survey Brochure BAM Service Brochure RAM RAM References Complete Literature Service Cases Repairs

 

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