Wednesday, December 19, 2007

6.6 Unexpectedly...

In major academic institutions, case reports do not rate as formal papers. The rationale is simple: each patient responds to a treatment differently, so they should not be reported piecemeal - case by case. With enough cases to show a trend and a strategy for reversing this trend, then they can be presented in toto as a research paper, so that others can learn from the experience.

In fact, very often the surgical procedure itself is described as being a big success, but then things start to go wrong. In very general terms, a quick description of some (not all) post-op problems is shown below:

1. Refractive surgery

Take, for example, LASIK:

Obviously if the correction is inaccurate, e.g., under- or over-correction, residual astigmatism, or regression, then the post-op vision won't be as good as advertised.

There are also glare, haze, and halo that can result from off-centered ablation, pupil size larger than the ablated zone, or folds in the flap.

Post-op dry eye, epithelial growth, inflammation, and infections are all possibilities.

2. Cataract extraction

Cataract surgery has a 95% success rate. It is still possible to develop catastrophic infection (known as endophthalmitis), intraocular hemorrhage, cystoid macular edema, or even retinal detachment.

3. Glaucoma shunts

After previously failed glaucoma surgeries, the last resort is a shunt implant. The principal complication after implanting the shunts is hypotony (low intraocular pressure). Healthy eyes will produce enough aqueous humor to fill up the shunt reservoirs. And the eye then re-pressurizes. However, choroidal detachments or hemorrhages can occur if the eye is not healthy (e.g., from diabetes).

4. Vitrectomy

Most patients experience improved vision after vitrectomy. However, about 18% of patients develop complications with half of them having zero improvement in vision, and the other half, actually permanent vision loss from, e.g., neovascular glaucoma (the main reason why the glaucoma shunts are needed).

5. EOM re-alignment (strabismus surgery)

The most common complications are under- and over-correction, so the eyes are still not straight post-operatively. Sometimes these are transient, but other times, another surgical correction is needed. Other complications include:

Perforation of the sclera
Lost and slipped muscles
Infection
Anterior segment ischemia (from damage to the ciliary arteries)
Diplopia
Conjunctival granulomas and cysts

6. Corneal transplant

As in all transplants, the biggest problem for cornea transplant is tissue rejection. This is treated with immunosuppressants at the early stage. Other possible complications include infection, hemorrhage, retina detachment, and glaucoma. Still other problems are optical, for example, irregular astigmatism can be a result. Irregular astigmatism cannot be corrected with spectacles at all; only RGP hard contacts can cover up the irregularity.

Fortunately, most if not all of the above post-op complications can be successfully repaired or treated; although the outcome will be somewhat less than that expected before the surgery.

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