Meacock WR, Spalton DJ, Bender L, Antcliff R, Heatley C, Stanford MR, Graham EM

Br J Ophthalmol 2004;88: 1122-4

Cataracts occur in up to 50% of patients with uveitis and ocular inflammation should be minimised for at least 2 months before proceeding with surgery. Additionally, these patients should receive increased preoperative immunosuppressive steroid prophy-laxis as this has been shown to increase the pro-portion of patients with a visual acuity (VA) of 20/40 or better at 3 months. The aim of this prospective randomised study was to compare the effects of a single dose of intravenous methyl-prednisolone given half an hour before surgery with a 2 week preoperative course of oral pred-nisolone on VA, blood-aqueous barrier recovery (BAB), and the incidence of angiographic CMO in patients with uveitis undergoing phacoemulsi-fication.

Forty uveitis patients with cataract underwent phacoemulsification and intraocular lens (IOL) implantation. Preoperatively they were randomised into two groups: group 1 (20 patients) received a single dose of intravenous methylprednisolone (15 mg/kg) half an hour before surgery, and group 2 (20 patients) received a 2 week course of oral prednisolone (0.5 mg/kg) which was tapered post-operatively. Preoperatively patients had aqueous flare and cells measured with the Kowa laser flare meter. On days 1,7,28, and 90 aqueous flare and cells were measured, and on days 7 and 90 fluorescein angio-graphy was performed to determine the incidence of cystoid macular oedema (CMO).

At all postoperative visits the mean increase in flare was greater for group 1 (intravenous steroid). Patients with posterior synechiae had greater blood-aqueous barrier damage (BAB) postoperatively. There were no statistically significant differences in logMAR visual acuity and incidences of CMO between the two groups at 7 and 90 days. In authors opnion a 2 week course of oral prednisolone, tapered postoperatively, produced a better recovery of the BAB than a single dose of intravenous methylprednisolone and is thus the recommended preoperative regimen.

Visual function in low birthweight children

O’ Connor AR, Stephenson TJ, Johnson A, Tobin MJ, Ratib S, Moseley M, Fielde r AR

Br J Ophthalmol 2004;88:1149-53

Preterm birth and retinopathy of prematurity (ROP) have both been reported to impact the developing visual system resulting in reduced visual acuity, diminished contrast sensitivity, and an increase in colour deficits. It has also been shown that these effects are not temporary that is, a delay in development consequent upon premature birth, but permanent, as they have been shown to persist into later childhood and even adult life. It is encouraging that many of these deficits are minor, so that individual values, although they differ significantly from the visual functions of children born at full term, usually fall within the normal range. Nevertheless, performance among preterm children considered as a group (mean value) is consistently and significantly lower than that of their peers born at full term.

Severe ROP is well known to affect visual functions with the loss ranging from mild to total, whereas the impact of mild ROP (stages I and 2) on visual function is less well defined. Studies have demonstrated a reduction in acuity associated with mild ROP, however, the multifactorial nature of the deficits in low birthweight children suggests that no single factor is the cause of this reduction. A comprehensive and intense ophthalmic examination protocol permits a detailed analysis of the impact of ROP on visual function even in cases of mild disease. This present study is a follow up of these low birthweight children at 10-12 years old. Follow up at this age allows for a comprehensive assessment of visual function with the aim of differentiating the effects of ROP from preterm birth alone. An overview of the ophthalmic outcome of this cohort has been reported previously but authors presented greater detail focusing on the visual functions including amblyopia. As this cohort is biased towards mild ROP these data will complement the existing knowledge on the outcome of children with threshold disease. The data will be helpful in deciding what provisions for long-term ophthalmic care are required.

The aims of this component of the study were to compare the visual acuity, contrast sensitivity, colour, and visual field data of a cohort of low birthweight children with a control group of children born at term. In addition, to analyse the relation between neonatal factors (including ROP) and later visual function. 572 low birthweight (LBW) "low birthweight cohort" children who had been examined in the neonatal period were invited for review at 10-12 years of age. 169 11 year old schoolchildren born at full term were also recruited, "school cohort." Visual acuity (at distance and near), contrast sensitivity, colour vision, and visual fields were measured.

293 of the original 572 participants consented to a further examination. Compared to the school cohort of children born at term the low birthweight cohort showed significantly lower near and distance acuities and contrast sensitivity (p<0.001 for all uniocular and binocular measures). Retinopathy of prematurity (ROP) was a very poor predictor of outcome and multivariate analysis did not identify any key neonatal factors as predictors of long term visual outcome. The authors concluded that low birthweight children have a small but statistically significant deficit in both visual acuity and contrast sensitivity. Low birth weight and ROP both impact on long term visual functions.

Glare sensitivity and optical side effects 1 year after photorefractive keratectomy and laser in situ keratomileusis

Neeracher B, Senn P, Schipper I

J Cataract Refract Surg 2004; 30:1696-1701

Treatment of myopia with photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) is now successful and popular. Although loss of best corrected visual acuity (BCVA) occurs rarely, reduction in contrast sensitivity and symptoms of glare, halos, and night-vision disturbances occur postoperatively.

The purpose of this study was to compare the outcome of low-contrast visual acuity and glare sensitivity after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). In this prospective study, patients selected PRK or LASIK after the ad­vantages and disadvantages of both had been described. Snellen visual acuity and disability glare were measured with the Berkeley glare test preoperatively and 1 year postoperatively. At the 1 year follow-up, haze was graded and patients had to assess their quality of vision subjectively.

One-year follow-up of 58 patients in the PRK group and 64 patients in the LASIK group was achieved. In both groups, the mean uncorrected visual acuity was 20/32 (P = .63) and the mean best corrected visual acuity, 20/20 with no statistically significant difference (P = .20). There were no preoperative or postop­erative differences between the 2 groups in low-contrast visual acuity under 4 glare conditions. At 1 year, LASIK eyes had significantly lower postoperative haze scores than PRK eyes (P = .0013). The number of eyes with visually moderate and disturbing halos or disturbances in night vision did not differ considerably between the groups (P = .88).

The authors concluded that efficacy outcomes were generally similar in the PRK and LASIK groups. Both achieved good objective and subjective results after treatment with a second generation excimer laser.

New formula for calculating intraocular lens power after laser in situ keratomileusis

Jarade EF, Tabbara KF

J Cataract Refract Surg 2004; 30:1711-5

An increasing number of patients who have photo-refractive surgery will need subsequent cataract extraction with intraocular lens (IOL) implantation. The IOL power calculation depends on the axial length (AL), anterior chamber depth (ACD), and keratometry (K) reading. After photorefractive surgery, the AL and ACD do not change, with few exceptions. Keratometry, on the other hand, may significantly change postoperatively. The current methods for measuring keratometry include manual keratometry, automated keratometry (auto-K), and corneal topography. However, these methods underestimate corneal flattening after radial keratotomy (RK), photorefractive keratectomy (PRK), and laser in situ keratomileusis (LASIK) by overestimating the K-reading. This may lead to a falsely low IOL power calculation with subsequent hyperopia after cataract surgery.

Many patients who have LASIK today will have cataract surgery in the future. These patients will remain highly motivated to have excellent uncorrected visual acuity after cataract surgery, just as they did after their refractive surgery. As such, it increasingly important to select an IOL power that gives optimal optical results. Therefore, accurate measurement of corneal dioptric power is crucial in the precise measurement of IOL power.

The purpose of this study was to assess the validity and accuracy of a proposed formula for keratometry (K) readings after laser in situ keratomileusis (LASIK). This study comprised 34 eyes that had LASIK surgery. Refraction and an automated K-reading (auto-K) were performed preoperatively. Refraction, auto-K, and K-reading assessment by the clinical history method and the proposed formula were performed 4 to 12 weeks postoperatively. The proposed formula is Kpostop = [(A/c - 1) X (Ra_postop - fta-preop)/(fta-postoP x Ra-Preop)], where Kposto is the K-reading after LASIK, Kpre0p is the K-reading before LASIK, Nc is the index of refraction of the cornea (1 .376), Ra _postop is the radius of curvature of the anterior corneal surface after LASIK, and Ra _preop is the radius of curvature of the anterior corneal surface before LASIK.

Twenty patients (10 men, 10 women) were included in the study. The mean age of the patients was 30.58 years ± 17.68 (SD) (range 18 to 44 years). Preoperatively, the mean spherical equivalent (SE) was -4.99 ± 2.82 diopters (D) (range -1.12 to -15.00 D), the mean Ra was 7.76 ± 0.32 mm (range 7.33 to 8.50 mm), and the mean auto-K reading was 43.45 ± 1.73 D (range 39.62 to 46.00 D). Postoperatively, the mean SE was +0.02 ± 0.63 D (range -2.75 to +1.00 D), the mean fla was 8.63 ± 0.53 mm (range 7.80 to 9.92 mm), and the mean K-reading assessed by auto-K, clinical history method, and the proposed formula was 39.17 ± 2.35 D (range 34.00 to 43.25 D), 38.79 ± 2.52 D (range 33.1 to 42.78 D), and 38.69 ± 2.51 D (range 33.1 to 43.0 D), respectively. The results obtained by the proposed formula were similar to those obtained by the clinical history method (P = .098). Auto-K readings significantly overestimated the K-values (P<.0001) when compared to the proposed formula and clinical history method.

In authors opinion the proposed formula is simple, objective, not dependent on refraction, and as accurate as the clinical history method in determining K-readings after LASIK.

Comparative clinical trial of topical anesthetic agents in cataract surgery

Lidocaine 2% gel, bupivacaine 0.5% drops, and benoxinate 0.4% drops

Soliman MM, Macky TA, Samir MK

J Cataract Refract Surg 2004; 30:1716-20

Topical anesthesia is widely accepted as the first choice in most cases of planned routine cataract surgery. Its introduction was made possible by the advent of clear corneal small-incision phacoemulsi-fication, in which manipulation of painsensitive ocular structures is minimal. The 3 main modes of topical anesthesia are eyedrops alone, eyedrops plus intracameral injection, and gel application. The main advantages of topical over injection anesthesia (retrobulbar, peribulbar, sub-Tenon's) are minimal pain during application, greater patient satisfaction, faster postoperative functional recovery, lower cost, and elimination of injection related complications such as retrobulbar hemorrhage, globe perforation, optic nerve injury, and ptosis. The main disadvantage is the need for good patient cooperation.

The purpose of this study was to assess the efficacy of lidocaine gel, bupivacaine drops, and benoxinate drops as topical anesthetic agents in cataract surgery. This prospective randomized study comprised 90 patients scheduled for routine cataract extraction. Patients were randomized into 3 groups of 30 each based on which anesthetic agent they received: lidocaine 2% gel, bupivacaine 0.5% drops, or benoxinate 0.4% drops. Subjective pain at application of the agent and intraoperatively was quantified by the patients using a verbal pain score (VPS) scale from 0 to 10. The duration of discomfort at application, duration of surgery, rate of supplemental sub-Tenon's anesthesia, and complica-tions were recorded.

The mean VPS at application was 2.97, 1.53, and 1.03 in the lidocaine, bupivacaine, and benoxinate groups, respectively; the VPS in the lidocaine group was statistically significantly higher than in the other 2 groups (P<.001). The mean duration of pain at application was 25 seconds, 14 seconds, and 6 seconds in the lidocaine, bupivacaine, and benoxinate groups, respectively, and was statis­tically significantly higher in the lidocaine group (P<.001). The mean VPS during surgery was 1.6, 4.1, and 7.1 in the lidocaine, bupivacaine, and benoxinate groups; the lidocaine group had a statistically significantly lower mean VPS than the other 2 groups (P<.001). The incidence of supplemental sub-Tenon's injection was 3.3%, 10.0%, and 73.3%, respectively, and was statistically significantly lower in the lidocaine and bupivacaine groups than in the benoxinate group (P<.001). The patients' overall satisfaction was statistically significantly higher in the lidocaine and bupivacaine groups than in the benoxinate group (93.3%, 83.3%, and 33.3%, respectively) (P<.001). Three patients in the lidocaine group had corneal haze at the time of sur­gery, which was not statistically significant (P>.1).

The authors concluded that lidocaine gel was a better topical anesthetic agent than bupivacaine and benoxinate drops. Bupivacaine drops were effective in providing deep topical anesthesia.

Fundus Autofluorescence in Stargardt Macular Dystrophy-Fundus Flavimaculatus

Lois N, Halfyard AS, Bird AC, Holder GE, Fitzke FW

Am J Ophthalmol 2004; 138:55-63

Stragardt macular dystrophy-fundus flavi-maculatus (STGD-FFM) is an inherited retinal dystrophy characterized by the presence of white-yellow deep retinal lesions, the so called flecks, in the posterior pole exclusively or extending to the midperipheral retina. Most patients will develop overt atrophic macular lesions. Functional abnor-malities in STGD-FFM include loss of macular function with or without loss of generalized cone, or cone and rod function. The disease is inherited as an autosomal recessive trait and it is caused by mutations in the ABCA4 gene.

Several histopathology studies found high levels of lipofuscin in the retinal pigment epithelium (RPE) in patients with STGD-FFM. Using a noninvasivc fundus spectrophotometer, Delori and associates1 demonstrated abnormally high fluorescence intensity, with the spectral characteristics of lipofuscin, in five patients with STGD FFM and dark choroid. Furthermore, using a confocal scanning laser ophthalmoscope (cSLO), von Ruck-mann and associates2 found high levels of fundus auto-fluorescence (AF), an index of lipofuscin content in the RPE, in all 27 patients with STGD-FFM examined, with or without dark choroid. In the above in vivo studies, levels of AF were quantified at selected areas of the retina. Thus, Delori and associates measured AF at 7 degrees temporal to the fovea and at the fovea, and von Ruckmann and associates between 7 and 15 degrees temporal to the fovea, where there were no focal changes in AF on fundus AF images.

The purpose of this observational, comparative study was to quantify autofluorescence (AF) levels in patients with Stargardt macular dystrophy-fundus flavimaculatus (STGD-FFM), across the macular region and to assess the relationship between levels of AF and retinal function as determined by pattern electroretinogram (PERG) and full field electro-retinogram (ERG) and to identify patterns of AF.

Patients were recruited at Moorfields Eye Hospital. Forty-three STGD-FFM patients aged 20 to 40 years and 35 age-matched normal volunteers. The right eye was chosen arbitrarily for measures of AF. The AF images were obtained using a confocal scanning laser ophthalmoscope. Levels of AF across the macula were measured. The distribution of AF was also evaluated. In 36 patients (84%) pattern electroretinogram (PERG) and full-field ERG were obtained and results were evaluated with respect to levels of AF.

The main outcome measure were the values of AF, AF distribution, PERG, and ERG. Normal or high AF at the center of the macula with high AF temporally or nasally or both was detected in 1 7 patients (39%). In nine (21 %), low AF at the center of the macula with normal or low AF temporally or nasally or both was found. Levels of AF were normal throughout the macula in six patients (14%). In 11 (26%), high, normal, and low levels of AF were found. All patients tested with low AF at the center of the macula and normal or low AF temporally or nasally or both had peripheral cone/rod dysfunction. None of the patients tested that had normal or high AF at the fovea and high AF temporally or nasally, or normal AF throughout the macula, had peripheral cone/rod dysfuncion.

The authors concluded that AF is not universally high in STGD-FFM. Some patients have normal or low AF. Autofluorescence patterns appear to relate to functional abnormalities.

Reference

1. Delori FC, Staurenghi G, Arend O, Dorey CK, Goger DG, Weiter JJ. In vivo measurement of lipofuscin in Stargardt’s disease-fundus flavimaculatus. Invest Ophthalmol Vis Sci 1995; 36:2327-31.

2. Von Ruckmann A, Fitzke FW, Bird AC. In vivo fundus autoflurescence in macular dystrophies. Arch Ophthalmol 1997; 115:609-15.

Photorefractive Keratectomy for Pediatric Anisometropia: Safety and Impact on Refractive Error/ Visual Acuity/ and Stereopsis

Paysse EA, Hamill MB, Hussein MAW & Koch DD

Am J Ophthalmol 2004; 138:70-8.

Excimer laser refractive surgery has been successfully used for treatment of myopia, hypermetropia, and astigmatism in adults. As advances in excimer laser surgery occur, new indications for refractive surgery are expected, including its use in children. One indication currently heing investigated is its use in treating children with anisometropia associated with amblyopia.

Amblyopia is the most frequent cause of visual impairment in children and young adults in the United States and Western Europe. Anisometropia is a major cause of amblyopia. Traditional treatment options for anisometropic amblyopia include refractive correction with spectacles or contact lenses and occlusion or optical and pharmacologic penalization of the sound eye. Children with severe refractive anisometropia are commonly intolerant to spectacle correction because of resultant aniseikonia and diplopia caused by refractive correction. Contact lenses, the other traditional treatment of anisometropia, are often difficult to use in children.

Few studies have heen published regarding the effect of photorefractive keratectomy (PRK) and laser in situ kera-tomileusis (LAS1K) in children. Most of these reports have heen done outside the United States and have typically included children older than 6 years, an age at which treatment of amblyopia is less successful. The purpose of this study was to establish the safety and possible efficacy of excimer laser photorefractive keratectomy (PRK) for treatment of pediatric anisometropia.

In this prospective, noncomparative intervene-tional case series at an individual university practice in which photorefractive keratectomy was done 11 children aged 2 and 11 years with anisometropic amblyopia who were unable or unwilling to use contact lens, glasses, and occlusion therapy to treat the amblyopia. The eye with the higher refractive error was treated with PRK using a standard adult nomogram. The refractive treatment goal was to decrease the anisometropia to 3 diopters or less. Main outcome measures were cycloplegic refraction, refractive correction, degree of corneal haze, uncorrected and best spectacle corrected visual acuity, and Stereopsis over 12 months.

All patients tolerated the procedure well. The mean refractive target reduction was -10.10 ± 1.39 diopters for myopia and +4.75 ± 0.50 diopters for hyperopia. The mean achieved refractive error reduction at 12 months for myopia was -10.56 ± 3.00 diopters and for hyperopia was +4.08 ± 0.8 diopters. Corneal haze at 12 months was minimal. Uncorrected visual acuity improved by 2 or more lines in 6 (75%) of the eight children able to perform psychophysical acuity tests. Best spectacle-corrected visual acuity improved by 2 lines in 3 (38%) of patients. Stereopsis improved in 3 (33%) of nine patients.

The authors concluded with remarks that pediatric PRK can be safely performed for anisometropia. The refractive error response in children appears to be similar to that of adults with comparable refractive errors. Visual acuity and Stereopsis improved despite several children being outside the standard age of visual plasticity. Photorefractive keratectomy may play a role in the management of anisometropia in selected pediatric patients.

The Long-term Results of Keratoplasty in Eyes with a Glaucoma Drainage Device

Alvarenga LS, Mannis MJ, Brandt JD, Lee WB, Schwab IR and Lim MC

Am J Ophthalmol 2004; 138:200-5

Many patients with corneal disease requiring penetrating keratoplasty (PK) have concurrent glaucoma. Although some patients can be controlled with topical medication, a glaucoma drainage device (GDD) has become an important method for controlling intraocular pressure (IOP) in the difficult cases. These devices have been successful in lowering IOP after PK ranging from 65% to 95%. Nevertheless, the presence of a GDD is considered by many to be associated with a worse prognosis for graft survival. The mechanism for graft failure in these patients is not fully understood. Mechanical trauma during the placement of a GDD or in the postoperative period caused by micromotion during eye movement and blinking or simply poor positioning of the GDD may cause endothelial damage. Moreover, the possibility of a change in immune status after the creation of a communication between the anterior chamber and the subconjunctival space has been hypothesized but remains unproven.

The effect of the presence of a GDD on the eventual outcome of corneal transplantation is difficult to establish because the devices are usually placed in eyes with poor glaucoma control, a factor independently associated with a poor prognosis for the corneal graft. The purpose of this study was to study the outcome of penetrating keratoplasty (PK) in eyes with a glaucoma drainage device (ODD). The authors reviewed all patients who underwent PK from December 1986 to September 2002 at the University of California, Davis (n = 1,974). We identified 33 patients (40 grafts) who were treated with a GDD and followed up for 6 months or more after PK. Graft survival and glaucoma control were compared with grafts in patients without glaucoma (n = 40) and patients with medically controlled glaucoma (n = 17). Kaplan-Meier survival analysis, log rank test, repeated-measures analysis of variance (ANOVA), Fisher exact test, and ?2 were used in group comparisons. Multivariate analysis was performed using the Cox proportional hazards model.

The percentages of clear grafts in the glaucoma drainage device group were 58.5% and 25.8% at 1 and 2 years, respectively. At these time points, glaucoma was controlled in 74.0% and 63.1% of the eyes, respectively. Both medically controlled glaucoma patients and nonglaucomatous patients had higher graft survival percentages at comparable time points. The presence of a GDD was an important factor influencing graft survival (Hazard ratio = 6.8). The authors concluded that a GDD implant is an independent risk factor for graft failure. Although these devices are effective in controlling intraocular pressure (IOP) in the majority of eyes in the presence of PK, corneal graft clarity is often compromised.