Review of Ophthalmology
The Alcon Toric intraocular lens is effective, as the acrylic material is “sticky” and virtually eliminates postop rotation. The downside is that it can be difficult to align with the intended axis.
The common approach is to insert the IOL and spin it just counterclockwise of the intended axis prior to full expansion of the haptics. Evacuate the viscoelastic and then nudge the IOL clockwise onto the axis marked on the cornea preoperatively. At this time the haptics will have contact with the fornices of the capsule and rotation will be difficult.
What to do when you have over-rotated the IOL? It’s a long way “around the horn” and not without risk, particularly in hyperopes with a small capsule and a lot of drag due to IOL-capsule contact.
A simple and easy way to back up the IOL (that is, spin counterclockwise) is to place the I/A tip under the superior aspect of the optic and go to irrigation, freeing the IOL optic and haptics from capsular contact. A Bechert rotator through the side port incision on the top of the IOL can spin the IOL in the reverse direction, using the I/A tip as its axis. Spin just to the right of the intended axis, and withdraw the I/A tip. Then, correct a few degrees clockwise to the planned axis.
The “reverse spin” is easier, faster and safer than rotating clockwise an additional 175 degrees with full IOL-capsule contact, and the attendant risks of zonular dehiscence or capsular rupture.
Saturday, March 7, 2009
Rhein Pre-Chopper for Smaller Incisions
Review of Ophthalmology
Rhein Medical has introduced a new Aguilar Pre-Chopper (Product #8-01349), developed in coordination with Roberto Aguilar, MD. Rhein says the instrument is ideal for pre-chopping grade III, IV and V cataracts. It features blades that are smaller, to easily pass through a 2.0 mm phaco incision, and beveled to allow pre-chopping with both anterior and posterior surfaces.
The pre-chopper is reusable, autoclaveable and made in the United States. There is a 30-day surgical evaluation without obligation and a complimentary instructional DVD. Call Rhein at (813) 885-5050 for more information.
Rhein Medical has introduced a new Aguilar Pre-Chopper (Product #8-01349), developed in coordination with Roberto Aguilar, MD. Rhein says the instrument is ideal for pre-chopping grade III, IV and V cataracts. It features blades that are smaller, to easily pass through a 2.0 mm phaco incision, and beveled to allow pre-chopping with both anterior and posterior surfaces.
The pre-chopper is reusable, autoclaveable and made in the United States. There is a 30-day surgical evaluation without obligation and a complimentary instructional DVD. Call Rhein at (813) 885-5050 for more information.
Consider Phaco for Some Glaucoma Patients
Eyenet
How do you normally treat glaucoma patients? Drops? Laser or scalpel surgery? According to Richard L. Lindstrom, MD, cataract extraction may be the appropriate procedure for most patients with combined cataract and glaucoma.
.......The researchers found that:
The higher the IOP at surgery, the greater the IOP reduction after surgery.
Age did not affect the magnitude of the IOP reduction.
74 percent of eyes with an IOP 20 mmHg converted to normotensive eyes (IOP 19mmHg) after surgery for the 10 years of the study.
77 percent of these eyes diagnosed with glaucoma had IOP 19mmHg after surgery for the 10 years of the study.
Pressure reductions achieved at one year were sustained for 10 years in all patient groups.
Dr. Lindstrom hypothesizes that age-related lens changes are a major cause of ocular hypertension, and eventually of glaucoma. Lens removal thus improves ocular outflow and reduces IOP. In advanced glaucoma, phaco/IOL surgery alone might be insufficient, and these patients with severe glaucoma damage or very high pressures may still do best with a combined procedure, he added.
How do you normally treat glaucoma patients? Drops? Laser or scalpel surgery? According to Richard L. Lindstrom, MD, cataract extraction may be the appropriate procedure for most patients with combined cataract and glaucoma.
.......The researchers found that:
The higher the IOP at surgery, the greater the IOP reduction after surgery.
Age did not affect the magnitude of the IOP reduction.
74 percent of eyes with an IOP 20 mmHg converted to normotensive eyes (IOP 19mmHg) after surgery for the 10 years of the study.
77 percent of these eyes diagnosed with glaucoma had IOP 19mmHg after surgery for the 10 years of the study.
Pressure reductions achieved at one year were sustained for 10 years in all patient groups.
Dr. Lindstrom hypothesizes that age-related lens changes are a major cause of ocular hypertension, and eventually of glaucoma. Lens removal thus improves ocular outflow and reduces IOP. In advanced glaucoma, phaco/IOL surgery alone might be insufficient, and these patients with severe glaucoma damage or very high pressures may still do best with a combined procedure, he added.
Watch for Patients With MRSA or MRSE
Eyenet
It is no longer just health care workers whom ophthalmologists should view as at risk for postoperative infection by antibiotic-resistant bacteria, according to a study of cataract surgery patients at 10 sites across the United States.Approximately half of the 399 patients in the study had preoperative lid or conjunctival presence of methicillinresistant forms of Staphylococcus epidermidis (MRSE) or S. aureus (MRSA).1 These are the most common pathogens causing endophthalmitis (S. epidermidis) after phacoemulsification and bacterial keratitis (S. aureus) after refractive surgery.........
Dr. Donnenfeld said that at the eye surgery center where he is medical director the anti-MRSE/MRSA protocols include:
Minimizing infection risk by treating even mild blepharitis before refractive surgery. He recommends a week of hot compresses, eyelid cleansing (SteriLid) and azithromycin 1 percent (Aza- Site) drops applied to the ocular surface and also rubbed into the lid margins, twice daily.
Beginning a fourth-generation fluoroquinolone on the day of LASIK rather than at the time of surgery. He continues the antibiotic for five days postoperatively.
Dosing with the antibiotic for three days before cataract surgery and 10 days after.
Using intracameral vancomycin during cataract surgeries.
Keratectasia After LASIK
December’s Archives
Meghpara et al. examined the histopathologic and immunohistochemical features of corneal buttons from patients who developed keratectasia after LASIK.
Five keratectasia corneal buttons were obtained during penetrating keratoplasty. Histologic features were examined by hematoxylin-eosin staining using paraffin-embedded sections and by transmission electron microscopy. Immunostaining for alpha1-proteinase inhibitor, Sp1, and matrix metalloproteinases 1, 2 and 3 was performed with two normal human corneas and two corneas with keratoconus as controls.
Central stromal thinning was observed after hematoxylin-eosin staining in all corneas with keratectasia. By transmission electron microscopy, collagen fibril thinning and decreased interfibril distance were observed in the stromal bed. However, no histologic features specific to keratoconus—including Bowman’s layer disruption—were identified in the corneas with keratectasia. Immunostaining intensity and/or pattern for alpha1-proteinase inhibitor and Sp1 in the corneas with keratectasia was comparable to that of normal control corneas but different from that of keratoconus. No significant staining with anti-matrix metalloproteinases 1, 2 and 3 antibodies was observed in either the corneas with keratectasia or the normal controls.
The authors conclude that post- LASIK keratectasia results in collagen fibril thinning and decreased interfibril distance within the residual stromal bed. Discrepant immunohistochemical findings between keratectasia and keratoconus suggest that the pathogenesis of the two conditions differ
Genetic and Environmental Links to Aging Visual Function
February’s Ophthalmology
Using a classical twin study, Hogg et al. investigated the relative contribution of genetic and environmental influences to the significant losses in visual function associated with normal aging.
They evaluated cone function in 42 pairs of twins (21 monozygotic and 21 dizygotic, ages 57 to 75) with normal visual acuity. Cone function was evaluated by establishing absolute cone contrast thresholds to flicker (4 and 14 Hz) and isoluminant red and blue colors under steady-state adaptation.
The researchers found a strong genetic contribution to cone absolute threshold, color (red and blue) and flicker (4 and 14 Hz) thresholds. However, the dynamic aspects of adaptation and the rod absolute thresholds demonstrated less genetic input—thus implying a greater potential influence from environmental factors.
They conclude that while many common visual parameters are inherited, other vital neuronal processes are significantly influenced by environmental factors over a lifetime—leading to new possibilities in preventing or delaying visual dysfunction or disease.
Adherence to Single-Dose Glaucoma Medication
February’s Ophthalmology
Okeke et al. have found that patient adherence with once-daily prostaglandin therapy for glaucoma is not substantially better than once-daily drops of beta blockers or four-times daily pilocarpine.
For this study, the researchers used the Travatan Dosing Aid that electronically records the time and date of a travoprost dose. Of the 196 patients with evaluable data at three months, 109 (55.6 percent) took more than 75 percent of the expected doses. Those who took less than 50 percent of expected doses showed significantly increased dose taking immediately after the office visit and just prior to the return threemonth visit. In addition, neither patient self-report nor physician estimation of adherence accurately reflected the true behavior as measured by the Travatan Dosing Aid.
The investigators conclude that 44 percent of participants who knew they were being monitored and were provided free medications nevertheless took less than 75 percent of the doses, suggesting that poor patient adherence remains a challenge in providing care to glaucoma patients
Okeke et al. have found that patient adherence with once-daily prostaglandin therapy for glaucoma is not substantially better than once-daily drops of beta blockers or four-times daily pilocarpine.
For this study, the researchers used the Travatan Dosing Aid that electronically records the time and date of a travoprost dose. Of the 196 patients with evaluable data at three months, 109 (55.6 percent) took more than 75 percent of the expected doses. Those who took less than 50 percent of expected doses showed significantly increased dose taking immediately after the office visit and just prior to the return threemonth visit. In addition, neither patient self-report nor physician estimation of adherence accurately reflected the true behavior as measured by the Travatan Dosing Aid.
The investigators conclude that 44 percent of participants who knew they were being monitored and were provided free medications nevertheless took less than 75 percent of the doses, suggesting that poor patient adherence remains a challenge in providing care to glaucoma patients
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