Lanjutan – 2, CATARACT SURGERY PREOPERATIVE EVALUATION

  • 24/06/2021
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III. EXAM

A. Introduction

A general overall view of the patient to determine surgically limiting fac- tors such as body habitus, kyphosis, or tremor should be observed. A complete dilated eye exam is necessary in all patients to determine surgical necessity and surgical planning. Special attention should be paid to lenticular stability.

B. Vision

1. Visual acuity

Snellen visual acuity has traditionally been one of the main indicators of the necessity of cataract surgery. However, Snellen acuity measures only high contrast discrimination in controlled lighting situations. This is not an ac- curate metric for patients who experience real world symptomatology such as glare or decreased color vision. Although poor Snellen acuity alone may be an indication for surgery, good Snellen acuity is not a contraindication for surgery. A complete assessment of visual function could include any or all of the following based on an individual’s symptoms: distance acuity, near acu- ity, binocular function to test anisometropia, glare testing, light testing, and contrast sensitivity. A potential acuity meter or interferometry may be used to determine visual potential.

C. Keratometry

Keratometry is used for IOL calculations and must be performed in both eyes as an internal control. Keratometric measurements also help determine corneal astigmatism and provide the basis for discussion of astigmatic treat- ments. As discussed previously, it is imperative to inquire about contact lens wear and previous refractive surgery before keratometric measurements.

D. Corneal Topography

Topography might be indicated in some circumstances:

  1. If keratometry values differ from the past, between eyes, or from therefraction.
  2. If corneal astigmatic procedures are planned (limbal relaxing inci- sions and astigmatic keratotomy).
  3. If considering a presbyopia-correcting or astigmatic-correcting lens.

E. Pupils

1. Afferent pupillary defect

Check all patients for an afferent pupillary defect (APD). Should a new APD be found, further work-up is warranted prior to surgery. Cataracts gen- erally do not cause an APD; however, it has been reported that dense cataracts can cause a contralateral APD.

2. Dilation

Poor dilation in the clinic suggests poor dilation during surgery and the surgeon should be prepared for this eventuality. Extremely large pupils predispose patients to glare and dysphotopsia. Appropriate IOLs should be chosen in these cases.

F. Intraocular Pressure

Significantly elevated intraocular pressures or narrow angles may require treatment before surgery.

G. Motility

1. Tropias

Patients with severe longstanding cataracts can develop tropias from sen- sory deprivation. If the deprivation is cured (ie, cataract removal), the patient may develop diplopia with his or her new binocularity and need prism glasses or additional strabismus surgery to treat the diplopia.

2. Trauma

Traumatic cataracts may also create a tropia; however, it may be traumatic and not sensory in origin.

3. Diplopia and ptosis

Diplopia and ptosis are known complications of cataract surgery, including topical surgery. It is important to document preexisting motility disorders.

H. External

A prominent forehead and/or deeply recessed globe may pose a techni- cal challenge to the cataract surgery procedure especially when performed superiorly.

I. Slit Lamp

A complete slit lamp examination with specific attention paid to the fol- lowing conditions will aid in the preoperative planning.

1. Lids/lashes

Blepharitis or meibomitis may increase risk of endophthalmitis and should be treated before surgery. Blepharophimosis can limit surgical exposure. Pto- sis can be exacerbated by speculum use.

2. Conjunctiva/sclera

The presence of prior surgery such as filtering blebs may alter the approach to surgery. Symblepharon, conjunctival scarring, or scleral thinning may alter the surgical approach as well. Conjunctivochalasis may make suction difficult to obtain if performing laser-assisted cataract surgery.

3. Cornea

Guttata may represent early Fuchs’ dystrophy, which can be made worse with cataract surgery, especially with extended phacoemulsification times. Corneal pathology such as scars or peripheral degenerations may alter the surgical approach. Pigment on the endothelial surface may be a clue to pseudoexfoliation.

4. Anterior chamber

Narrow angles with elevated IOP may require laser peripheral iridotomy before cataract surgery. If anterior chamber IOL placement is likely, gonioscopy is necessary to look for peripheral anterior synechiae or angle neovascularization.

5. Iris

Determine maximal dilation and check for posterior synechiae. Debris present at the pupillary margin may represent pseudoexfoliation.

6. Lens

Determine cataract density to plan the surgical approach. Check for lenticular stability by either having the patient look back and forth quickly or hitting the slit lamp table while observing the lens. Identify lenticular dislocation or subluxation. Pseudoexfoliation is most obvious on the anterior lens capsule. In addition, check for posterior polar cataracts as they are associated with increased risk of posterior capsular rupture with vitreous loss.

7. Anterior vitreous

Asteroid hyalosis and vitreous hemorrhage can make visualization very difficult in the operating room.

As an adjunct to complete slit lamp examination, retinoscopy can provide valuable information regarding the visual impact of cataracts that are unim- pressive at the slit lamp.

J. Fundus

Patients need to be dilated for a cataract evaluation.

1. Retina

Any retinal pathology such as age-related macular degeneration (AMD), epiretinal membrane (ERM), vitreomacular traction, macular hole, scars, or diabetic retinopathy that could be responsible for decreased vision should be identified and discussed with the patient to give him or her appropriate expectations for postoperative vision.

2. Optic nerve

The optic nerve should also be thoroughly evaluated for pallor or cupping and treated or referred appropriately.

3. Ultrasonography

Should cataract density prevent adequate visualization of the posterior pole, B-scan ultrasonography should be used to rule out gross abnormalities such as tumors or retinal detachments.

K. Orbit

The orbit should be examined and the surgeon should visualize the ideal approach for surgery when making the preoperative plan. Deep orbits may preclude a superior or superonasal incision, limiting the ability to operate on the steep keratometric axis. In addition, excessively deep or narrow orbits may prevent suction in conjunction with laser-assisted cataract surgery.

L. Neuropsychiatric

Comprehension and ability to follow commands during the examination are clues to how the patient will behave in the operating room. Patients who are not able to follow commands should be offered general anesthesia. Pa- tients who are extremely visually demanding or prone to bitter complaints of glare and halo inconsistent with the exam should probably avoid multifocal lenses.

*Dikutip dari Buku Essentials of Cataract Surgery 2nd Ed, halaman 14-18

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