Pseudophakic Bullous Keratopathy

Cataracts

94 million people are blind or visually impaired globally, and cataract is the most common cause of blindness worldwide. However, most cases of blindness are avoidable. Cataract is associated with decreased quality of life and reduced life expectancy. Most cases of cataract occur after birth and share ageing and oxidative stress as primary causes, although several non-modifiable and modifiable risk factors can accelerate cataract formation. In most patients, phacoemulsification with intraocular lens implantation is the preferred treatment and is highly cost-effective. There has been an increase in the use of comprehensive cataract surgical services, including diagnoses, treatment referrals, and rehabilitation. However, global inequity in surgical service quality is still a limitation. Implementation of preoperative risk assessment, risk reduction strategies, and new surgical technologies have made cataract surgery possible at an earlier stage of cataract severity with the expectation of good refractive outcomes. The main challenge is making the service that is currently available to some patients accessible to all by use of universal health coverage.

Pseudophakic corneal edema: A review of mechanisms and treatments

PURPOSE

To review the pathological mechanisms and treatments for pseudophakic corneal edema (PCE), one of the most common indications for penetrating keratoplasty.

METHODS

The literature was examined for the molecular biology associated with PCE and for the surgical and medical treatments for this disorder.

RESULTS

The incidence of PCE has recently been decreasing because of improved surgical instrumentation, including improvements in intraocular lens designs that cause less trauma to the corneal endothelium. Extracellular matrix and growth factor abnormalities occur in PCE corneas and recently, the role of aquaporins, which are involved in the regulation of fluid movement across cells, has been investigated.

CONCLUSIONS

Although newer treatment options have been suggested, penetrating keratoplasty still remains the most definitive treatment and has the highest success rate.

Incremental cost-effectiveness of initial cataract surgery

PURPOSE

The purpose of this study was to perform a reference case, cost-utility analysis of initial cataract surgery using the current literature on cataract outcomes and complications.

DESIGN

Computer-based econometric modeling.

METHODS

Visual acuity data of patients treated and observed over a 4-month postoperative period was obtained from the US National Cataract Patient Outcomes Research Team (PORT). The results from this prospective study were combined with other studies that investigated the complication rates of cataract surgery to complete the cohort of patients and outcomes. These synthesized data were incorporated with time-tradeoff utility values, decision analysis, and econometric modeling to account for the time value of money.

MAIN OUTCOME MEASURES

The number of quality-adjusted life-years (QALYs) gained was calculated for the study group undergoing cataract extraction in the first eye when the vision was the same in both eyes. This was divided into the cost of the procedure to find the year 2000 nominal US dollars spent per quality-adjusted life-year ($/QALY) gained.

RESULTS

Initial cataract surgery, compared with observation, resulted in a mean gain of 1.776 QALYs per patient treated. A 3% annual discount rate was used to account for the benefit over time, yielding 1.25 QALYs gained. The mean cost of treatment (also discounted at a 3% annual rate) of each patient totaled 2525 US dollars. The cost divided by the discounted benefit resulted in $2020/QALY gained for this procedure.

CONCLUSIONS

Initial cataract surgery seems to be highly cost-effective compared with procedures across multiple medical specialties. This information, incorporating patient preferences into evidenced-based medicine, will play an increasingly important role in the evaluation of health care in the future.

Lens implant selection with absence of capsular support

If contact lens or spectacle correction is not viable, little debate exists that the secondary placement of an intra-ocular lens (IOL) is the method of choice in the absence of capsular support. The choice of IOL mainly depends on the preoperative status of the eye (eg, aphakia in children) and the selected location for the implant. Theoretically, there are several IOL implantation approaches in cases without capsular support: an angle-supported anterior chamber (AC) IOL, an iris-fixated ACIOL, an iris-sutured or iris-fixated posterior chamber (PC) IOL and a transsclerally sutured PCIOL. No consensus exists, however, on the indications as well as on the relative safety and efficacy of these different options. Implantation of modern ACIOLs, like the refined open-loop or iris-fixated claw (toric) ACIOLs, have regained popularity and provide a valuable alternative to sutured PCIOLs. However, in the absence of capsular support, the transsclerally sutured PCIOLs offer numerous advantages for certain eyes. Because of its anatomic location, the sutured PCIOL is more appropriate for eyes with compromised cornea, peripheral anterior synechiae, shallow anterior chamber, or glaucoma. Moreover, sutured PCIOLs are appropriate if the patient with aphakia is young or has a life expectancy of 10 years or more. Recent technological advances, including PCIOL with iris diaphragm for aniridia, toric ACIOLs, and small-incision surgery with foldable, transsclerally sutured IOLs, seem to further improve clinical outcomes.

Long-term follow-up of leiske closed-loop anterior chamber intraocular lenses

PURPOSE

To provide long-term follow-up on the rates of endothelial cell loss in eyes with retained closed-loop anterior chamber intraocular lenses (IOLs).

SETTING

Private practices, Chicago, Illinois, USA.

METHODS

In 1980 to 1982, 3 surgeons performed 587 intracapsular cataract extractions with implantation of Leiske closed-loop anterior chamber IOLs. During the prospective part of the study from 1991 to 1996, 59 patients with 83 eligible eyes were followed using specular microscopy and pachymetry. The mean follow-up of the prospective study was 41.9 months, or 12.9 years from the original cataract surgery.

RESULTS

No specific preoperative or postoperative factor except the behavior of the fellow eye (P =.022) predicted the rate of endothelial cell loss. During the prospective study, 6 patients required IOL exchange and corneal transplantation. The rate of corneal decompensation was heavily dependent on the initial measurement of endothelial cell density. Corneas with initial endothelial cell counts greater than 1000 cells/mm(2) had a decompensation rate of 1.5%, and corneas with counts of 500 cells/mm(2) or less had a decompensation rate of 57.1% (P <.01).

CONCLUSIONS

Clinical examination and serial measurements of endothelial cell density provide the most reliable methods for monitoring patients with closed-loop anterior chamber IOLs. Endothelial cell counts can predict the rate of corneal decompensation. Patients with endothelial cell counts greater than 1000 cells/mm(2) usually do not require an IOL exchange.

Iris Claw Phakic Intraocular Lens for High Myopia

BACKGROUND

The implantation of a Worst-Fechner iris claw intraocular lens (IOL) is one of the surgical procedures used for the correction of high myopia. This technique reduces myopia with stable refractive results; however, its potential long-term risks have not been evaluated. We report results in 94 eyes with a minimum follow-up of 3 years.

METHODS

We studied 94 eyes of 62 patients with myopia > or = -7.00 diopters (D) who underwent Worst-Fechner IOL implantation. Lens decentration, permeability of the blood-aqueous barrier by iris angiography, and changes in corneal endothelial density were analyzed.

RESULTS

Mean follow-up time was 48.9 months (range 36 to 72 mo). Three years after surgery, 58 eyes (61%) had an uncorrected visual acuity > or = 20/40, and 77 eyes (82%) gained two or more lines of spectacle-corrected visual acuity with respect to the preoperative value; 75 eyes (79%) were within +/- 1.00 D of emmetropia and 46 eyes (48%) were within +/- 0.50 D of emmetropia. The mean endothelial cell loss was 17.9% at 5 years after surgery, while the percentage of hexagonality and the coefficient of cell variation tended toward preoperative levels. No vision threatening complications were seen.

CONCLUSIONS

The implantation of a Worst-Fechner iris claw phakic IOL reduced high myopia with a stable refractive outcome. Endothelial cell damage was within acceptable limits. The absence of major complications makes this procedure an acceptable method for correcting high myopia.

Penetrating keratoplasty and transscleral fixation of posterior chamber lens

We reviewed the charts of 21 patients who underwent penetrating keratoplasty and transscleral fixation of a posterior chamber lens. One lens was sutured in an aphakic eye and 20 lenses were sutured after removal of an anterior chamber lens. Postoperative follow-up averaged 13 months (2-39 months). Visual acuity improved in 20 patients (95%) and remained the same in 1 patient (5%). Postoperative visual acuity was less than 0.1 in 5 patients (23.8%), 0.1 to 0.33 in 14 patients (66.7%) and better than 0.33 in 2 patients (9.5%). Twelve patients (57.1%) expressed a substantial reduction in ocular pain, 7 patients (33.3%) had no pain either before or after the operation, 2 patients (9.5%) expressed no reduction in pain. No cases of endophthalmitis, choroidal hemorrhage or retinal detachment were found. In one case, the sutured lens was dislocated without disturbing vision. Intraocular pressure increased in 3 of 9 patients with preoperative glaucoma. New-onset glaucoma developed in 1 patient. We find transscleral fixation of a posterior chamber lens to be an acceptable procedure in penetrating keratoplasty with IOL implantation where capsular support is inadequate for conventional implantation of a posterior chamber lens.

Penetrating keratoplasty for pseudophakic corneal oedema

AIMS

The study was designed to investigate the results of penetrating keratoplasty (PK) for pseudophakic corneal oedema (PCO).

METHODS

Retrospective analysis of 80 consecutive patients (82 eyes) who underwent PK for PCO between the years 1980-1992 with a minimum follow up of 12 months.

RESULTS

PKs for PCO have accounted for as many as 20% of all grafts performed in the hospital in recent years. The interval between cataract extraction and PK ranged from 6 to 161 months (mean 51 months). The intraocular lens was removed in 45 (55%), left in situ in 30 (37%), and exchanged in seven (8%) of cases respectively. Of the intraocular lenses involved 62% were iris supported, 31% angle supported, and 7% were posterior chamber lenses. Actuarial analysis shows graft survival to be 91% at 1 year and 86% at 2 years after surgery. The likelihood of graft survival was significantly enhanced by removal of the intraocular lens (p < 0.01). A corrected Snellen visual acuity worse than 6/60 was present in 36% of patients with a clear corneal graft. Ocular comfort was achieved in all patients with a clear corneal graft.

CONCLUSION

PK for PCO resulted in a disappointing visual result in a large proportion of patients. PK was, however, successful in relieving pain and corneal ulceration when present.

Are there acceptable anterior chamber intraocular lenses for clinical use in the 1990s? An analysis of 4104 explanted anterior chamber intraocular lenses

PURPOSE

The authors pose the question as to whether there are any anterior chamber intraocular lenses (AC IOLs) acceptable for clinical use in the 1990s.

METHODS

Data on the incidence and types of complications of 4104 AC IOLs that were submitted to the Center for IOL Research from 1982 to 1993 were retrieved from the laboratory database and analyzed using cumulative frequency calculations and the chi-square test. Normalized explantation rates were related to implantation rates that were derived from market-share analysis.

RESULTS

Of 4104 explanted IOLs, 50% were closed-loop designs (n = 2095/4104); 26% (1100/4104) were miscellaneous, older designs; and 22% (919/4104) were open-loop lenses. The most important complications were corneal pathology (2065/4104) and inflammation (1370/4104). Closed-loop designs were responsible for almost 80% of corneal pathology, with an increasing complication rate with ongoing implant duration (P < 0.0001). Open-loop AC IOLs showed, in relation to their normalized rate of implantation, a significantly lower rate of complications and explantations (P < 0.01).

CONCLUSION

Complication rates of flexible, open-loop AC IOLs are much lower than previously assumed. They should be distinguished clearly from most older AC IOL designs. Consideration of these lenses as an alternative to sutured posterior chamber IOLs for secondary or exchange implantation may be warranted for selected clinical indications. They also could provide an alternative to the aphakic spectacle rehabilitation program in developing countries, which will have a positive impact on the overwhelming backlog of patients with cataract in the underprivileged world.

Changing indications for penetrating keratoplasty

The indications for penetrating keratoplasty have changed over the past several years. One hundred and eighty cases of penetrating keratoplasty performed in the Department of Ophthalmology, Naestved Centralsygehus, Denmark, from January 1984 to December 1993, were analysed. Overall pseudophakic bullous keratopathy was the most common indication for penetrating keratoplasty (28.3%). This was followed by keratitis (13.9%), Fuchs' dystrophy (13.9%), regraft (11.1%), aphakic bullous keratopathy (10.0%) and keratoconus (6.7%). Pseudophakic bullous keratopathy was the most common indication for penetrating keratoplasty in 1989 and in each year from 1991 to 1993. Before 1989 the most common indications were keratitis (18.0%) and aphakic bullous keratopathy (14.8%). The emergence of pseudophakic bullous keratopathy, as the most common indication for penetrating keratoplasty, correlates well with the dramatic increase in the number of cataract extractions with intraocular lens implantation performed since the early 1980s. Especially semiflexible, closed-loop anterior chamber lenses used in our department in the early years of the period, have been the cause of subsequent corneal edema.

Penetrating keratoplasty for pseudophakic bullous keratopathy associated with closed-loop anterior chamber intraocular lenses

Closed-loop anterior chamber intraocular lenses (AC IOLs) are associated with a high incidence of pseudophakic bullous keratopathy (PBK). The prognosis for recovery of vision with penetrating keratoplasty and the exchange of one type of AC IOL for another remains controversial. A total of 40 consecutive patients with closed-loop AC IOLs and varying degrees of PBK underwent penetrating keratoplasty, explanation of the closed-loop AC IOL, and implantation of a flexible tripod AC IOL--all done with a uniform technique. The average follow-up study was 24 months. Average preoperative visual acuity was 20/170 (range, 20/25-hand motions) and average postoperative visual acuity was 20/44 (range, 20/20-no light perception). A total of 23 eyes (57.5%) achieved a visual acuity of 20/40 or better. Eleven eyes (27.5%) had a visual acuity of 20/200 or worse. Persistent cystoid macular edema was the most frequent cause of poor vision postoperatively (4 eyes), followed by age-related macular degeneration (3 eyes) and graft rejection (2 eyes). This is the first series documenting a good visual outcome for at least 2 years after penetrating keratoplasty and exchange of a closed-loop AC IOL for a single type of flexible tripod AC IOL.