Optimizing the intraocular lens formula constant according to intraocular lens diameter.

AIM: To determine whether the different diameters of a specific intraocular lens (IOL) have significantly different optimized SRK/T A constants and whether these new A constants can improve refractive outcomes. METHODS: Data were collected prospectively from Jan. 2011 to Dec. 2012 on all patients undergoing routine cataract surgery at a district general hospital in the UK. Patients were divided into three groups according to the size of the Akreos AO MI60 IOL used. A constants for the SRK/T formula were optimized according to the size of the IOL. These optimized A constants were then used to select future refractive outcomes. RESULTS: A total of 2398 cataract operations were performed during the study period of which 1131 met the inclusion criteria. The three optimized A constants for the different sized IOLs were 118.98, 119.13, 119.32. The difference between them was highly significant (P≤0.0001). Two optimized A constants for three sizes of IOL led to an improvement in refractive outcomes (from 93.4% to 94.6% of refractive outcomes within 1.00 D of predicted spherical equivalent). The optimized A constant for the largest IOL was based on a small number of cases and was not used. CONCLUSION: Optimizing the A constant for the three distinct sizes of the Bausch & Lomb Akreos MI60 lens lead to three significantly different A constants. In our practice, using two different optimized A constants for three different sized IOLs give the least refractive error, however, using three optimized A constants may give better results with a larger dataset.

TANDEM TRIAL: a factorial randomised controlled trial of dose and review schedule of bevacizumab (Avastin) for neovascular macular degeneration in the East Midlands.

OBJECTIVE: Neovascular age-related macular degeneration (nAMD) causes damage to the macula and severe vision loss. Bevacizumab is the most cost-effective nAMD treatment. The TANDEM trial was designed to determine whether, in patients with nAMD, low-dose bevacizumab is non-inferior to the standard dose in terms of visual deterioration and whether a bimonthly regimen is non-inferior to monthly, treatment as required, regimens. METHODS: This was a multicentre, 2×2 factorial, double-masked, non-inferiority randomised trial with patients considered eligible if they met the National Institute for Health and Care Excellence criteria for nAMD treatment with ranibizumab. Participants were randomly assigned to standard (1.25 mg) or low (0.625 mg) dose bevacizumab and either monthly or bimonthly review regimen. The primary outcome was time to vision deterioration, defined as reduction of ≥15 letters (three lines) during the loading phase (visual acuity scores at visits B and C compared with the initial visit A), or ≥6 letters (one line) during the maintenance phase (visual acuity scores at subsequent visits compared with mean vision at visits A-C). RESULTS: In total 812 participants (918 eyes) were randomised into the trial. The low dose showed some evidence of being non-inferior to standard dose (HR 1.07; 95% CI 0.80 to 1.42), however, there was no strong evidence of bimonthly review being non-inferior to monthly review (HR 1.45; 95% CI 1.09 to 1.94). There was no difference in visual acuity when assessed at 9 months and no major differences in the frequency of serious adverse events or reactions between the groups. CONCLUSION: The standard dose of bevacizumab can be halved without compromising efficacy. Bimonthly review cannot be considered to be no worse than monthly review.

Comparing different dosing regimens of bevacizumab in the treatment of neovascular macular degeneration: study protocol for a randomised controlled trial.

BACKGROUND: Bevacizumab (Avastin®) is as effective as ranibizumab (Lucentis®) in the treatment of neovascular age-related macular degeneration (nAMD). However it has two important structural differences. First, it has two active sites instead of one; second, it retains the Fc portion of the antibody which would be expected to confer a significantly longer half-life. These agents have been associated with systemic complications including strokes, so it is desirable to use the smallest effective dose. Furthermore, the standard dosing regimen requires monthly hospital visits, which present a significant challenge both to the hospital services and to the patients (who are elderly). METHODS/DESIGN: Patients ≥50 years who are eligible for anti-vascular endothelial growth factor (VEGF) treatment of nAMD in the NHS, who are either newly referred for treatment or have reactivation of nAMD and who have not received treatment to either eye for the previous six months. We have designed a factorial multi-centre masked randomised controlled trial using bevacizumab as the intervention, with patients randomised to one of four arms: to standard or low dose and to monthly or two-monthly patient review. The aim is to recruit sufficient patients (around 1,000) to obtain 304 patients meeting the endpoint over a four-year period. The primary endpoint is time to treatment failure to be analysed using Cox regression. DISCUSSION: This randomised control trial will show if half dose and two monthly as required is as effective as full dose and monthly regimes. A two monthly as required regimen of Bevacizumab would significantly reduce both the cost and the service delivery burden for the treatment of nAMD while a reduced dose would be expected to enhance the safety profile of this treatment regime. TRIAL REGISTRATION: International Standard Randomised Controlled Trial Number: ISRCTN95654194 , registered on 22 September 2009.

Subconjunctival lidocaine before laser treatment: a randomized trial.

PURPOSE: The aim of the study was to determine whether subconjunctival anesthesia is effective at reducing pain associated with laser retinopexy. DESIGN: This was a single-center, prospective, patient-masked, randomized, controlled trial. PARTICIPANTS: In the primary study group, 65 patients were recruited. Thirty-two patients (32 eyes) received anesthetic injection, and 33 patients (33 eyes) received the sham injection. The crossover study group consisted of 28 patients (56 eyes). METHODS: Between February 2008 and April 2008, all patients who were consecutively booked to undergo panretinal photocoagulation (PRP) or peripheral laser retinopexy (PLR) were invited to participate in the study. Patients were randomized to receive subconjunctival lidocaine injection or a sham injection before their intended laser retinal treatment. These patients were defined as our primary study group. Patients who required a second laser treatment received the opposite injection in a masked fashion before laser retinal treatment. These patients were defined as our crossover group. Patients in both the primary study group and the crossover group were masked to the treatment given. After the laser treatment, patients completed a pain questionnaire. MAIN OUTCOME MEASURES: The primary outcome was incidence of pain. The secondary outcome was severity of pain. RESULTS: Primary study group: In the anesthetic treatment group, 19 patients (59%) experienced pain compared with 32 patients (97%) in the sham treatment group (P<0.001). Among the patients who did experience pain, the average pain score was 3.6 in the anesthetic treatment group and 4.1 in the sham treatment group (P=0.55). Crossover study group: In the anesthetic treatment group, 12 patients (43%) experienced pain compared with 28 patients (100%) in the sham treatment group (P<0.001). In patients who did experience pain, the average pain score was 3.3 in the anesthetic treatment group and 4.6 in the sham treatment group. Twenty patients (71%) preferred anesthetic to sham treatments, 1 patient (4%) preferred sham over anesthetic, and 7 patients (25%) thought both laser treatments were the same. CONCLUSIONS: Subconjunctival 2% lidocaine significantly reduces the incidence of pain in patients who receive PRP or PLR.

Successful treatment of a serous retinal pigment epithelial detachment by coiling of a carotid-cavernous fistula.

PURPOSE: To report a patient presenting with a symptomatic retinal pigment epithelial detachment (RPED) that resolved after successful treatment of a slow flow dural carotid cavernous fistula (CCF). Possible pathophysiological mechanisms are discussed. METHODS: Interventional case report. RESULTS: A 69-year-old female presented with left uniocular distortion, confirmed on fluorescein and indocyanine green angiography to be secondary to a non-vascularised serous RPED. Further examination revealed a long standing left VI nerve palsy, mild proptosis and conjunctival injection. Magnetic resonance and cranial angiography confirmed the presence of a dural CCF. Surgical closure of the CCF resulted in a rapid resolution of the clinical signs and improvement in visual symptoms. CONCLUSIONS: Patients with serous RPED and other signs or symptoms of a CCF may warrant neuroimaging of the orbit and/or angiography to evaluate for CCF, as correct diagnosis may lead to an excellent visual outcome.