FUndus evaluation and special test for preoperative cataract surgery

1. 08-03-2024 / Faradhillah A. Suryadi

2. FUNDUS EVALUATION
 The ophthalmologist must perform a full fundus examination to evaluate the macula,
optic nerve, vitreous, retinal vessels, and retinal periphery. Particular attention is
paid to macular degeneration or other maculopathy that may limit visual outcome
after an otherwise uneventful cataract extraction.
 The indirect ophthalmoscope is not generally useful for judging the visual significance
of cataract, except in severe cases such as when the cataract is white. Although the
direct ophthalmoscope, retinal contact lens, and noncontact fundus lens are more
useful in judging media clarity, the ophthalmologist must keep in mind that these
methods also provide light that is more intense than that available to the patient
under ambient lighting conditions.
Ophthalmoscope

3.  Patients with diabetes mellitus are examined carefully for the presence of macular
edema, retinal ischemia, and background and proliferative retinopathy. Even in
uncomplicated cataract surgery and in patients with minimal or no retinopathy,
diabetic eye disease can progress postoperatively.
 Retinal ischemia may potentiate posterior or anterior neovascularization
postoperatively, especially if the surgeon uses an intracapsular technique or ruptures
the posterior capsule during extracapsular cataract extraction.
 Careful examination of the retinal periphery may reveal the presence of vitreoretinal
traction or preexisting retinal holes and lattice degeneration that may warrant
preoperative treatment.

4. Examination of the optic nerve includes assessment of cupping and
pallor, as well as any other abnormalities. Visual acuity, measurement of
IOP, and the results of confrontation testing and the pupillary
examination will help determine whether other adjunctive testing is
warranted.
Optic Nerve

5. B-scan ultrasonography of the posterior segment of the eye is useful
whenever a dense cataract makes visualization of the retina impossible.
Ultrasonography can elucidate whether a retinal detachment, vitreous
opacity, posterior pole tumor, or staphyloma is present.
Tests such as light projection, 2-point discrimination, gross color vision,
photostress recovery, blue-light entoptoscopy, or the Maddox rod test
may also be useful in detecting retinal pathology.
Electroretinography and visually evoked response testing could also be
considered when other modalities are inconclusive and the surgeon must
decide whether cataract removal would provide any benefit.
Fundus evaluation with opaque media

6. SPECIAL TEST
 Potential acuity estimation can be helpful in assessing lenticular contribution to vision loss. The potential acuity
pinhole test is a simple but accurate method of evaluation for patients who do not have other ocular pathology and
whose visual acuity is better than 20/200. For this test, the patient is asked to read a brightly illuminated near card
through a pinhole aperture. The Retinal Acuity Meter, or RAM (AMA Optics), functions in a similar manner.
 The Potential Acuity Meter, or PAM (Mentor Graphics/Marco), is one of several instruments that project a numerical
or Snellen vision chart through a small entrance pupil. The image can be projected onto the retina, around lenticular
opacities, allowing for an estimate of what the BCVA would be if the media abnormality were absent.
 It is important to note that these tests can be misleading in patients with certain disorders, including age-related
macular degeneration, amblyopia, macular edema, glaucoma, small macular scars, and serous retinal detachment.
 An accurate clinical examination of the eye is often the best predictor of visual outcome.
Potential Acuity Estimation

7.  It is important to perform confrontation field testing in all cataract patients,
but formal visual field testing is not indicated for every patient with lens
opacity. Visual field testing may help the ophthalmologist identify vision loss
resulting from disease processes other than cataract.
 Patients with a history of glaucoma, optic nerve disease, or retinal
abnormality may benefit from visual field evaluation to document the degree
of visual field loss. Preoperative visual field loss does not preclude
improvement in visual function following cataract surgery. Progressive
cataracts may induce diffuse visual field depression that disappears after
cataract removal.
Visual Field Testing

8.  In patients with a history of endothelial dystrophy, previous ocular surgery, or trauma,
additional corneal measurements may be useful. These data may aid the surgeon in
counseling the patient regarding the possibility of postoperative corneal decompensation.
In some cases, consideration of a combined surgery incorporating removal of the cataract
and transplantation of corneal tissue may be in order.
 Corneal pachymetry, a method employed to measure corneal thickness, is useful for
indirectly assessing the function of the endothelium. Significantly increased central
corneal thickness (>640 μm) in patients with endothelial dysfunction is associated with a
greater risk of postoperative corneal decompensation.
 Specular microscopy is used to determine corneal endothelial cell density per square
millimeter and evaluate these cells' regularity. Because cataract surgery results in some
loss of endothelial cells, the risk of postoperative corneal decompensation is increased if
the preoperative endothelial cell count is low. Abnormal endothelial cell morphology,
including enlargement (polymegathism) and irregularity (pleomorphism), may limit the
cornea’s ability to maintain its clarity after the stress of cataract surgery.
Assesment of Corneal Endothelial Function

9.  Optical coherence tomography (OCT) is increasingly performed as part of the
preoperative testing regimen for cataract surgery in the United States.
 It may be useful in the assessment or detection of macular pathology, including
neovascularization, edema, holes, and traction. Screening macular OCT to detect
occult macular pathology may be of particular benefit for patients undergoing surgery
with premium IOLs or when their vision is poorer than the degree of cataract would
suggest.
Objective Test of Macular Function