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
Cataract
Alone: Excellent Predictions (95%)
Co-Morbid Disease: Poor
Predictions (50%)
B. PAM (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.
Mild
to Moderate Glaucoma: Excellent
Predictions (91 to 100%)
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.
Co-morbid
Disease: Poor Predictions (50%) 
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.
Cataract
Alone: Excellent Predictions (r = 0.77)
Co-Morbid Disease:
Excellent Predictions (r = 0.77 & r = 0.58) 
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%)
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%) 
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%) 
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%) 
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%)
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%)
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%)
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%) 
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%)
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, 1345–1351.
Cataract Alone: Very Good
Predictions (87%)
Co-Morbid Disease: Excellent Predictions (93%) 
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%) 
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)
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%)
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%) 
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%) 
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%) 
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%)
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, 1345–1351.
Cataract Alone:
Excellent
Predictions (94%)
Co-Morbid Disease: Excellent Predictions (93%) 
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 Surgery. J
Korean Ophthalmol
Soc.
2007 Jul;48(7):898-904
Cataract Alone:
Excellent
Predictions (91.6%)*
Co-Morbid Disease: Excellent Predictions (90.9%)*
*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%)
F. PAP (Potential Acuity Pinhole) (Useful
0/1
study)
K
Melki, S.A., et. al: Potential acuity pinhole.
Ophthalmology 106, 1262-7, 1999.
Cataract Alone:
Excellent
Predictions (100%)
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%)
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%) 
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%)*
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%)
