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Biomedical subjects

B L Halliday

Publications and source records attributed to B L Halliday.

14 recordsLinked to original sources
PubMed1991

Surgical management of essential blepharospasm.

We have reviewed the surgical management of essential blepharospasm over the last 15 years, comparing the results from facial nerve avulsion with those from orbicularis muscle stripping. After facial nerve avulsion 50% of patients remained free of troublesome spasm for 15 months after surgery, but only 25% remained so for more than two years. Following orbicularis oculi myectomy 50% of patients were free of troublesome spasms for 30 months after surgery and 55% of patients had relief from spasm for more than two years. Secondary effects of the two procedures are compared and are found to be fewer after orbicularis myectomy. There were no major complications after either form of surgery. Botulinum toxin is the treatment of first choice for this condition. If this becomes ineffective or inconvenient, surgical treatment is warranted and should not be deferred for fear of severe side effects of treatment, since these are rare. Protractor myectomy gives longer relief from blepharospasm than facial nerve avulsion and has fewer complications. However, it is technically difficult, time consuming, and has greater peroperative morbidity. Facial nerve avulsion may therefore still have a role in selected patients.

Adult↗
PubMed1990

Epikeratophakia for keratoconus.

Results of the author's first 15 cases of epikeratophakia for keratoconus are presented. All patients were intolerant of contact lens correction and could not achieve satisfactory acuity with spectacle correction due to corneal ectasia and irregular astigmatism. The average follow-up was 13 months. Seventy-three per cent of eyes treated had a pre-operative spectacle acuity of 6/60 or worse. One eye had a preexisting amblyopia that limited final acuity, but every other eye achieved a post-operative spectacle acuity of 6/12 or better and 50% achieved 6/6. One eye had 11 dioptres of post-operative astigmatism and required penetrating keratoplasty; the remaining eyes had an average astigmatism of 1.9 dioptres. Epikeratophakia appears to be a safe alternative to penetrating keratoplasty in selected cases.

Adolescent↗
PubMed1990

Effect of donor parameters on primary graft failure and the recovery of acuity after keratoplasty.

A retrospective evaluation was made of 983 penetrating corneal grafts. Donor corneas stored in either K-Sol or McCarey-Kaufman media had a significantly greater rate of primary graft failure (about 2%) than those kept in moist chamber storage (0%). Selected subgroups of 50 corneas from each storage system were studied to determine the time taken to reach a postoperative acuity of 6/12. No significant correlation was found between this time and either the duration of storage of donor corneas or the age of donor. A significant delay in recovery of visual acuity was found with increasing age of recipient. The increased average time from donor death to surgery for K-Sol (56 hours) and McCarey-Kaufman (40 hours) corneas compared with moist chamber corneas (15 hours) facilitated the scheduling of surgery at the cost of increased chance of primary graft failure.

Adult↗
PubMed1990

Epikeratophakia for aphakia, keratoconus, and myopia.

A series of 67 cases of epikeratophakia is presented with an average time from surgery of 12.2 months. For aphakia there was a delay in the recovery of vision, but by nine months 83% of 57 patients achieved an acuity equal to, or within 1 line of, the preoperative value. 57% were corrected to within 3 dioptres of emmetropia, but in the latter part of the series 75% were within this range. Astigmatism and reduced contrast sensitivity, especially in the presence of glare, were important complications. For keratoconus, 86% of seven patients with over two months of follow-up achieved a spectacle corrected acuity of 6/9 or better. One patient had surgery for myopia and obtained the desired refractive correction.

Adolescent↗
PubMed1989

Glare and contrast sensitivity in contact lens corrected aphakia, epikeratophakia and pseudophakia.

The effects of glare on contrast sensitivity and high contrast Snellen acuity were investigated in a group of unilaterally aphakic patients with normal fellow eyes. In spite of relatively good visual acuity and apparently satisfactory surgical results, there was a marked reduction in contrast sensitivity in epikeratophakia and contact lens corrected aphakic eyes, relative to fellow normal eyes, especially in the presence of glare (P less than 0.05). Although the results from the pseudophakic patients were more variable, there is some evidence to suggest that epikeratophakia provides inferior visual function to contact lens correction or intraocular lens implantation. The results also suggest that the measurement of visual acuity in the presence of glare fails to identify many patients with a functional visual impairment secondary to glare.

Adolescent↗
PubMed1989

Simplified formulas for lathing aphakic epikeratophakia lenses.

Geometrically based formulas for lathing aphakic epikeratophakia lenses have been simplified to enable easy calculation of the radii of cut for the optical and the wing zones. The formulas compensate for postoperative thinning of the lens on host cornea and allow for any desired amount of pre-lathing dehydration. Clinical results to date show that over 80% of lenses are made within 3 diopters of the expected power.

Aphakia↗
PubMed1988

Manufacture of epikeratophakia lens.

Epikeratophakia lenses may be manufactured from donor cornea either with a lathe or using devices that make flat cuts on to previously deformed cornea. Details are given of a manufacturing technique using a cryolathe, including the storage and preparation of donor corneas and derivation of the formulae used to determine the radius of lathe cut.

Aphakia↗
PubMed1988

A new surgical head rest.

A surgical head rest is described that gives good wrist support, provides space to place instruments, and allows drainage of irrigation fluid.

Head↗
PubMed1986

Precarved lyophilized tissue for lamellar keratoplasty in recurrent pterygium.

Thirteen eyes with recurrent pterygia were treated with excision and lamellar keratoplasty using precarved, lyophilized donor cornea. After an average follow-up of 23 months, only one eye (7.7%) required repeat excision. Two eyes (15.4%) had minor recurrences that were asymptomatic and did not progress. Minimal vascularization at the interface between donor and recipient cornea was frequent, but this completely regressed after suture removal and topical corticosteroid treatment. Limitation of movement, when present preoperatively, was improved or eliminated. Best corrected visual acuity was unchanged in eight eyes (61.5%), decreased by one line in two eyes (15.4%), and improved by one or two lines in three eyes (23.1%). Postoperative astigmatism was within 0.5 diopter of the preoperative value in 11 eyes (84.6%); one eye (7.7%) had a postoperative increase of 1 diopter and another eye (7.7%) of 2 diopters.

Adult↗
PubMed1986

Calculation of intraocular lens power--results in practice.

There have been many reports describing the use of formulas to derive lens implant power in cataract surgery. Typically over 80 per cent of patients are said to have a final refraction within one dioptre of the desired value. In our clinical practice results are worse. Modification of the formula to suit an individual surgeon and implant style would probably improve results.

Humans↗