Bifocal contact lenses in presbyopia.
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Contact Lenses↗
Biomedical subjects
W S Van Meter
Publications and source records attributed to W S Van Meter.
Long-term safety of polypropylene knots under scleral flaps for transsclerally sutured posterior chamber lenses.
PURPOSE: To evaluate the safety of polypropylene knots used in TS-SPCL combined with PK and AV over time. METHOD: A retrospective review of 26 consecutive cases of TS-SPCL by one surgeon (WSVM) with at least 12 months follow-up (mean 26, range 12-62). All patients had a double strand polypropylene knot buried under partial thickness scleral flaps at 2 and 8 o'clock. Knots were rotated into the globe (R) in 10 cases, and could not be buried (N) in 13 cases, and in 3 cases 1 knot was buried. RESULTS: No cases of suture erosion occurred in R or N. One or more polypropylene sutures were visible in 17 patients (8 R, 9 T) at last exam. Twenty-three of 52 knots were rotated into the globe, and 70% of rotated knots were not even visible at the slit lamp at final visit. There was no evidence of conjunctival erosion in any patient. There was no lens dislocation and no endophthalmitis. CONCLUSION: The combination of partial thickness scleral flaps with double strand polypropylene knots reduces the incidence of suture erosion through the conjunctive if knots cannot be rotated into the globe.
Adult↗
Incidence and management of complications of transsclerally sutured posterior chamber lenses.
Thirty eyes with an average follow-up of 23 months following transscleral fixation of a posterior chamber intraocular lens (IOL) were retrospectively reviewed for complications. The most common complication was erosion of the polypropylene suture knots through half thickness scleral flaps (22 eyes, 73%). The average time for suture erosion through the sclera was 9.4 months (range one to 12). The polypropylene suture knots eroded through the conjunctiva in five eyes (17% incidence) at an average of 12 months postoperatively (range six to 18 months). All conjunctival erosions were surgically repaired. Other complications included clinically significant lens tilt/decentration (3/30, 10%), open angle glaucoma (5/30, 17%), and suprachoroidal hemorrhage (1/30, 3%). The complications associated with transscleral fixation of posterior chamber IOLs are distinctly different from those associated with anterior chamber IOLs. Prospective clinical trials may provide further information about pseudophakic rehabilitation in the absence of capsular support.
Adult↗
Clinical evaluation of the anterior constant focus (ACF) annular bifocal contact lens.
We evaluated the distance and near vision of 33 presbyopic patients who wore the Anterior Constant Focus (ACF) rigid gas permeable (RGP) bifocal lens. Twenty-seven patients (82%) wore the lenses for one year; the six patients who quit the study complained of unacceptable vision (four patients) and discomfort (two patients). Twenty-five patients (76%) obtained 20/25 or better distance vision, and 28 patients (85%) obtained J2 or better near vision. Contrast sensitivity was within normal limits in 24 of 33 (73%) patients. We feel the ACF lens provides good bifocal vision in a non-translating RGP design.
Contact Lenses↗
A clinical evaluation of two multifocal soft contact lenses.
We fit two multifocal soft contact lenses, Bausch & Lomb's Bi-Tech and the Unilens contact lens from Unilens Corporation, in two separate populations of presbyopes. Most patients (24/42, 57%) had no prior contact lens experience. Patients were evaluated at 6 and 12 months for comfort, visual acuity, lens fit, and corneal findings. Both distance and near vision were found to be slightly decreased with each contact lens when compared to best corrected visual acuity with spectacles. Seventy-seven percent (14/18) of the Unilens wearers and 67% (16/24) of the Bi-Tech wearers continued to wear their lenses for at least 1 year. Those who discontinued lens wear did so because they were dissatisfied with their vision. Presbyopes who seek correction with soft contact lenses appear to be more tolerant of a decrease in distance vision than a decrease in near vision. Both lenses were comfortable and no corneal pathology was induced. Our results suggest that the Unilens (simultaneous vision design) provides more predictable correction of presbyopic symptoms than the Bi-Tech (alternating vision design) because it is independent of lower lid position and translation. Both of these lenses are viable options for the correction of presbyopic symptoms.
Contact Lenses, Hydrophilic↗
Penetrating keratoplasty for corneal perforation in an obtunded patient.
A ventilator-dependent patient obtunded from severe head trauma suffered a spontaneous corneal perforation with lens extrusion secondary to nosocomial Pseudomonas keratitis. Despite the patient's guarded condition, a successful tectonic penetrating keratoplasty with lens removal was performed for restoration of the globe. Upon recovery, the patient's only useful vision was in her operated eye. Preventative measures against prolonged corneal exposure in an obtunded patient include copious artificial tears and lubricants, use of scleral lenses, moisture chambers, bandage contact lenses, or tarsorrhaphies.
Aged↗
An evaluation of four multifocal contact lenses in young monocular aphakic patients.
To evaluate the efficacy of multifocal contact lenses in the correction of presbyopic symptoms we fit six young monocular aphakic patients with four different bifocal contact lenses (ACC, Tangent Streak, VFL, and Constavu). Each patient had 20/20 uncorrected vision and normal accommodation in the other eye. We evaluated both subjective and objective parameters of comfort and vision for all four lenses. We found no significant overall performance advantage among the four lenses based on comfort, visual satisfaction, visual acuity, contrast sensitivity, or wear-related corneal complications.
Adolescent↗
Suture adjustment for postkeratoplasty astigmatism.
Excessive corneal astigmatism following penetrating keratoplasty is a frequent problem. A technique that adjusts a single running 10-0 nylon suture after keratoplasty was used in this series of patients. The procedure requires a keratometer, slitlamp, topical anesthesia, and tying forceps. In 52 eyes, with an average of 10.0 diopters of keratometric astigmatism, we adjusted the suture to flatten the steep corneal axis. We were able to reduce astigmatism an average of 7.2 diopters and this remained stable three months post wound revision.
Adult↗
Postkeratoplasty astigmatism control. Single continuous suture adjustment versus selective interrupted suture removal.
Two different suturing techniques performed during keratoplasty were retrospectively evaluated to compare postkeratoplasty astigmatism, number of suture manipulations, and time to optical stability. One group of patients (n = 31) received a combination of continuous 11.0 nylon suture and 12 or 16 interrupted 10.0 nylon sutures (CCIS), which were selectively removed post-operatively to reduce astigmatism. The second group of patients (n = 26) received a single continuous 10.0 nylon suture (SCS) that was adjusted postoperatively at the slit lamp to regulate corneal astigmatism. Compared with the CCIS technique, adjusting the single continuous suture resulted in less postoperative astigmatism (SCS, 1.5 +/- 1.1 diopters [D]; CCIS, 3.2 +/- 1.9 D), fewer suture manipulations per patient (SCS, 0.9 +/- 0.7; CCIS, 3.8 +/- 1.8), and earlier optical stability for visual rehabilitation (SCS, 2.6 +/- 1.5 months; CCIS, 9.6 +/- 4.7 months) (P less than 0.01). No continuous sutures were broken during adjustment. The adjustable single continuous suture may offer an improved method for early control of postkeratoplasty astigmatism.
Astigmatism↗
Histologic study of eyes with transsclerally sutured posterior chamber intraocular lenses.
We studied the postmortem histologic characteristics of two eyes that had undergone penetrating keratoplasty and transscleral suturing of a posterior chamber intraocular lens for bullous keratopathy. The eyes were studied three days postoperatively in a 79-year-old man with pseudophakia and six months postoperatively in an 83-year-old man with aphakia. We also removed a posterior chamber intraocular lens in a 73-year-old woman who had an epithelial downgrowth three months postoperatively. In the first two cases, only one of four haptics was successfully positioned in the sulcus. Histologic study disclosed a thin fibrous capsule surrounding the haptics at their attachment site, no inflammation around the transscleral portion of the suture, and exposure of a suture tip externally. In the third case, the intraocular lens fell back into the vitreous cavity after the fixation sutures were cut externally at the time of surgical removal. Stability of the lens in all three cases was primarily a result of intact transcleral sutures and not fibrous encapsulation or ciliary sulcus placement of haptics.
Aged↗
Penetrating keratoplasty after scleral patch graft.
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Adult↗
Suture adjustment for postkeratoplasty astigmatism.
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Astigmatism↗
Scanning electron microscopy of corneal incisions using steel, diamond, and sapphire blades.
In order to compare the wound morphology they produce, we used steel (Myocure), diamond (CILCO DK 121), and sapphire (Katena K2-6500) blades, to make parallel linear incisions, 500 microns deep, in 12 fresh enucleated porcine eyes. There was no discernible difference among the blades in terms of either the morphology of the collagen lamellae of the sides or the depth of the incisions produced. The major differences in the cuts produced were attributable primarily to the differences in the footplates.
Animals↗
Vitreous loss rates in extracapsular cataract surgery by residents.
Vitreous loss is a serious complication of cataract surgery. It has been suggested that high rates of vitreous loss may be an inevitable consequence when residents are learning extracapsular cataract extraction (ECCE). The authors retrospectively analyzed all (n = 936) cataract operations done by second- and third-year residents in a single Veterans Administration hospital from 1982 through 1988. Between 1982 and 1985, the incidence of vitreous loss was 10.3%. In 1985, a new program of resident surgical education was introduced, and the incidence from 1985 through 1988 declined to 3.2% (P less than 0.001). Statistical analysis confirms that this decrease cannot be attributed to any individual surgeon, class of residents, or year of surgery. The authors believe that an educational program including practice surgery, graded responsibility, and experienced assistance may be responsible in part for dramatically reducing the rate of this serious complication during surgery done by the beginning resident.
Cataract Extraction↗
Laser trabeculoplasty for glaucoma in aphakic and pseudophakic eyes after penetrating keratoplasty.
We used argon laser trabeculoplasty to treat medically uncontrolled glaucoma after penetrating keratoplasty in ten eyes that were aphakic or pseudophakic. These patients were examined over an average of 22.8 months (range, 12 to 37 months) after treatment. We found an average decrease in intraocular pressure of 9.1 mm Hg (range, +8 to -19), from an average of 30.6 mm Hg before treatment to an average of 21.5 mm Hg after treatment. Eight of ten eyes had a reduction of greater than 5 mm Hg, and six of ten eyes had intraocular pressure of less than 20 mm Hg. Visual function remained stable, and complications were rare. We now prefer argon laser trabeculoplasty to cyclocryotherapy for the initial treatment of patients with medically uncontrolled glaucoma who have predominantly open angles and a clear penetrating keratoplasty.
Aged↗
The triple procedure. Analysis of outcome, refraction, and intraocular lens power calculation.
Presented are the results of 66 consecutive, elective, combined procedures of penetrating keratoplasty, extracapsular cataract extraction, and intraocular lens insertion (triple procedure) performed by three surgeons between January 1981 and January 1984. After a mean postoperative followup of 15.8 months, over 90% of the eyes had clear grafts, and of the 56 eyes with good preoperative visual potential, 77% achieved a best corrected visual acuity of 20/40 or better. The postoperative mean refractive deviation from emmetropia was 2.17 diopters, with a range of +6.62 D to -5.50 D, 62% falling between -2.00 and +2.00 diopters. Using multiple regression analysis of preoperative and postoperative variables, an attempt was made to derive a predictive formula for the power of the intraocular lens to be implanted during the triple procedure. In contrast to cataract surgery, where axial length and corneal power remain fairly constant preoperatively and postoperatively, penetrating keratoplasty produces marked changes in corneal curvature and power. Therefore, a single formula could not be derived to predict accurately the intraocular lens power for the patients. However, using the results for an individual surgeon, a formula was derived that could improve the predictability of intraocular lens power.
Aged↗
Contrast sensitivity in extended wear of the Boston IV lens.
Over a one-year period we evaluated subjective and objective factors associated with extended wear of Boston IV rigid gas permeable contact lenses. Patients wore the lens on an extended wear schedule, with removal at 2-week intervals for cleaning. We performed keratometry and endothelial cell counts and measured visual acuity, contrast sensitivity, refraction, and corneal thickness at the initial visit (with patients wearing their former glasses or soft or hard lenses) and again at 6 and 12 months (with patients wearing the Boston IV lens). Twenty-four of 31 patients (77%) completed the study. All measured parameters were checked for statistically significant change over time. Contrast sensitivity increased at all spatial frequencies tested, with the largest increments occurring at higher frequencies (P less than .001). The other parameters showed no significant changes (P greater than .05). Our data support the use of contrast sensitivity for qualitative assessment of visual function among contact lens wearers and suggest that contrast sensitivity testing may prove to be a more effective means of evaluating visual acuity in contact lens wearers over time than Snellen acuity.
Cell Count↗
Clinical evaluation of three bifocal contact lenses.
The ACC, Alges, and Tangent Streak bifocal contact lenses were fit in separate populations of presbyopic patients, some of whom had not previously worn contact lenses. Complete eye examinations were performed on fitting and at 6 and 12 months after fitting to determine how effectively the lenses corrected presbyopic symptoms. Patients were examined for subjective comfort, visual acuity, contrast sensitivity, and by slit lamp. Sixteen of the 24 ACC lens wearers (67%), 23 of 31 Alges lens wearers (74%), and 25 of 27 Tangent Streak lens wearers (93%) wore their lenses comfortably after 12 months. Nine of 18 failures (50%) were successfully refit in one of the other bifocal lenses. Most patients read 20/25 and J1 with contrast sensitivity in the normal range at distance and near. Twelve of 16 patients (75%) with no prior contact lens experience continued to wear the lenses at 12 months. We believe that bifocal contact lenses provide an acceptable alternative for the correction of presbyopia. Lens fitting requirements and patient selection are discussed.
Adult↗