Wednesday, June 17, 2009

Retinitis Pigmentosa and Cataract Surgery

RP is a collection of many different genetic diseases that lead to progressive photoreceptor loss and associated vision loss; therefore, the etiology is remarkably variable

formulas for determining the power of the IOL,, ( for those with RP, caution, machine should be set differently, which is part of the problem I am left with, I have the wrong lens power implanted )
On RP and cataract surgery
Several medical conditions can predispose patients to the development of significant anterior capsular contraction syndrome. The best known and probably most commonly encountered of these conditions is pseudoexfoliation. Other pathologies include a history of uveitis, retinitis pigmentosa, high myopia, myotonic dystrophy, advanced age, and trauma (including ocular surgery). Subtle zonular damage, which most likely occurs from previous surgery such as trabeculectomy or vitrectomy, allows for progressive changes after cataract extraction in some cases. Diabetes mellitus is sometimes implicated in this condition as well, although this relationship appears to be less direct. It is certain, however, that zonular disease or trauma is closely associated with the problem of pathologic capsular contraction. Also, instability of the blood aqueous barrier appears to be an inciting factor in pathologic capsular contraction. A history of any of these situations should alert the surgeon to approach the procedure with caution and consider surgical techniques.8-11
While complicated surgery accounts for most cases of CME, this condition also occasionally occurs after straightforward surgery.
The more complicated the surgery, the greater the degree of CME and vision reduction

Good site on studies of RP and related problems,

This site explains how high risk patients ( rp is high risk ) should be given a special regiment both before and after undergoing cataract surgery( Of course Dr Porter didn't do that for me which is why I developed cme from the surgery )

and more on dosing preop and post op

For at-risk patients, Dr. Raizman said he begins the NSAID 1 week preoperatively and continues the regimen for at least 4 weeks to 6 weeks postoperatively. Patients presenting with diabetic retinopathy should receive non-steroidal treatment for at least 8 weeks preoperatively. OCT can serve as a guide for determining the duration of the therapy.
O’Brien TP. Emerging guidelines for use of NSAID therapy to optimized cataract surgery patient care. Curr Med Res & Opin. 2005;21;1131-1137.
McColgin AZ, Raizman MB. Efficacy of topical diclofenac in reducing the incidence of postoperative cystoid macular edema. Invest Ophthmol Vis Sci. 1999;40:289.
this article will describe erg tests, if you are getting erg tests from your eye doc, you should be light/dark adapted first ( yet another thing that Downing and McPeak center doesn't understand is that with RP you should be given time to adapt to the light situation before most testing )

Evaluating whether it is RP or the cataract interfering with your vision and determing the outcome
more on dislocation risks up to 20 yrs later with rp
Cataract surgery is contraindicated when it will not
improve visual function due to the presence of coexisting ocular disease.
However, cataract surgery may be necessary to improve visualization of
the posterior segment for treatment of coexisting disease

3. Supplemental Testing
Additional testing may be necessary to assess and document the extent of
the functional disability and to determine whether other diseases (e.g.,
corneal disease, optic nerve disease, or retinal disease) may limit
preoperative vision or may prove to limit postoperative vision.49,50
Contrast sensitivity, glare testing, potential acuity testing, threshold
visual fields or Amsler grid testing, fluorescein angiography, corneal
pachymetry/endothelial cell count, specialized color vision testing, Bscan
ultrasonography, tonography, and electrophysiology testing are not
required as a part of the preoperative workup; however, individual
circumstances, as documented in the patient record, may justify their use
Supplemental Testing to Document the Presence of
Coexisting Eye Disease, the Extent of Functional Disability,
and Potential for Improvement
Visual Fields
• Suspicion or evidence of retinal detachment, eye tumor, glaucoma, retinitis
pigmentosa, coloboma, optic nerve disease, or tumor
Amsler Grid
• Suspicion of macular disease
Corneal Pachymetry/Endothelial Cell Count
• History of previous corneal transplant or corneal surgery
• Suspicion of corneal thickening or endothelial dystrophy
• Planned phacoemulsification
B-Scan Ultrasonography
• Poor or limited view of the fundus
• History or suspicion of intraocular mass or tumor
• Suspicion of glaucoma or diagnosed open angle glaucoma
Specialized Color Vision Testing
• Suspicion of optic nerve or macular disease
• Suspicion of optic nerve disease
• Family history of retinal disease
• Assessment of visual function in a patient with a mature cataract
Contrast Sensitivity and/or Glare Testing
• Patients' symptoms of functional disability far worse than suggested by
visual acuity measurements
Potential Acuity Testing
• Prediction of postoperative acuity
( I wish that Dr Porter had been savvy enough to have performed these tests, before you decide to do surgery with RP, have these done, and make sure that the surgeon has gone over the results with you )

Government site on Retinitis Pigmentosa as a rare disease

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