Biomedical subjects

John Landers

Publications and source records attributed to John Landers.

8 recordsLinked to original sources

PubMed2006

A comparison of diagnostic protocols for interpretation of frequency doubling perimetry visual fields in glaucoma.

BACKGROUND: Frequency doubling perimetry (FDP) shows good correlation with achromatic automated perimetry in the assessment of glaucoma. However, many recommended protocols lead to a significant number of false positives and negatives. Therefore, it may be difficult to identify visual field loss owing to glaucoma. We investigated the accuracy of a diagnostic protocol that only considered either temporal wedge, arcuate, or nasal step field loss on an FDP field as significant. METHODS: Sixty-eight subjects who were glaucoma suspects, glaucoma patients or normal controls were recruited selectively. After achromatic automated perimetry and FDP visual field testing, results were compared between a conventional protocol and ones that took into account the position of FDP visual field loss. RESULTS: If an FDP field was considered abnormal only when either a temporal wedge, an arcuate or a nasal step defect was present, the presence of a nasal step yielded the most accurate results with the least false positives (kappa coefficient=0.76) and with only minimal increase in false negatives, compared with a conventional FDP protocol (kappa coefficient=0.70). CONCLUSIONS: Although, not statistically significant in this case, our results suggested a trend that a diagnostic protocol which considers nasal step FDP field loss significant may have a greater degree of accuracy when compared with conventional protocols and may facilitate interpretation in a clinical setting.

Female↗

PubMed2006

Causes of blindness among hospital outpatients in Ecuador.

BACKGROUND: There is a lack of published information on the causes of blindness in Ecuador and the Latin American region in general. This study is designed to enumerate the proportions of ocular conditions contributing to blindness in an outpatient population of an ophthalmology hospital in the coastal region of Ecuador. METHODS: All cases presenting to an ophthalmology outpatient clinic over a 3-week period during September 2004 were reviewed (n = 802). Visual acuity was measured using a Snellen acuity chart and those who met the criteria for blindness were included in the study (n = 118). Blindness was defined under the World Health Organization protocol as visual acuity of <3/60. Both unilateral and bilateral blindness were included in the study. The diagnosis of ocular pathology contributing to blindness was recorded. RESULTS: Among those considered to have unilateral blindness (n = 88), cataract was the most common cause (43%). This was followed by corneal pathologies (17%) and glaucoma (15%). Among those considered to have bilateral blindness (n = 30), refraction was the most common cause (37%), followed by cataract (23%) and glaucoma (17%). CONCLUSION: The major causes of blindness found in this study reflected those in estimated data for the region. More studies are needed to improve the quality and quantity of epidemiological data on blindness in Ecuador and Latin America. Many obstacles to successful implementation of prevention of blindness programmes in South America still need to be overcome.

Adolescent↗

PubMed2006

Decompression retinopathy and corneal oedema following Nd:YAG laser peripheral iridotomy.

Decompression retinopathy has been reported as a rare occurrence, subsequent to Nd:YAG laser peripheral iridotomy for the treatment of acute angle closure. Herein a case of a 67-year-old woman is described who developed decompression retinopathy in conjunction with unexpectedly severe corneal stromal oedema following Nd:YAG laser peripheral iridotomy for acute angle closure. The literature regarding these phenomena is reviewed.

Aged↗

PubMed2005

Choice of intraocular lens may not affect refractive stability following cataract surgery.

PURPOSE: To assess whether the choice of an intraocular lens (IOL) with rigid haptics (Sensar) or an IOL with pliable haptics (Acrysof) has an effect on refractive stability following cataract surgery. METHODS: Seventy-three patients were recruited consecutively as they returned for their 6-month visit following cataract surgery. There were 37 patients who had received an Acrysof IOL and 36 who had received a Sensar IOL. Each patient had their refractive error measured at the 1-month postoperative visit. At the 6-month follow-up visit, refraction was repeated. The change in refractive error was then compared between IOL groups and other factors that may affect postoperative refractive stability including preoperative refraction, axial length, keratometry, wound type and wound meridian. RESULTS: An Acrysof IOL showed minimal myopic movement, whereas a Sensar IOL was more likely to move hypermetropically. However, this difference was not statistically significant (t=1.92; P=0.06). The magnitude of the shift in spherical equivalent in either direction for the Acrysof group was 0.37 +/- 0.35 D and for the Sensar group was 0.28 +/- 0.31 D. Again, this difference was not statistically significant (t=1.17; P=0.25). However, preoperative anterior chamber depth was associated with postoperative refractive shift (t=2.66; P=0.009). Furthermore, patients with a scleral wound showed a small against-the-rule shift in cylindrical refractive error. No other factors were associated with postoperative refractive shift amongst the sample. CONCLUSIONS: There were no clinically significant differences in postoperative refractive stability between the Acrysof and Sensar groups. However, preoperative anterior chamber depth was associated with the magnitude of shift in spherical equivalent.

Acrylic Resins↗

PubMed2005

Prevalence of cicatricial trachoma in an indigenous population of Central Australia: the Central Australian Trachomatous Trichiasis Study (CATTS).

BACKGROUND: Trachoma is one of the leading causes of blindness worldwide, resulting from conjunctival scarring, upper lid entropion and trichiasis, leading to corneal scarring and opacification. This study was designed to investigate the current prevalence of cicatricial trachoma in an indigenous population within Central Australia and help determine whether trachoma remains a public health issue. METHODS: Participants aged 40 and over were recruited from patients attending one of 16 remote ophthalmology clinics held at indigenous communities in Central Australia within the Northern Territory. Once informed consent had been obtained, each patient underwent examination for evidence of trachomatous scarring, trachomatous trichiasis and corneal opacities. Results were collated and compared with previous prevalence surveys. RESULTS: Among the sample (n = 181), there were 97 patients (54%; 95% CI 46.7-61.3) with trachomatous scarring, 15 patients (8%; 95% CI 2.8-13.2) with trichiasis and 5 patients (3%; 95% CI 0.5-5.5) with corneal opacities. CONCLUSION: This study suggests that, although the prevalence of the cicatricial and blinding consequences of trachoma may be decreasing in patients aged 40 years or greater, when compared with the current prevalence in other areas of Australia, trachoma still remains a public health issue in Central Australia.

Adult↗

PubMed2004

A visual field abnormality: ocular or cerebral cause?

The visual field can be affected by disorders involving any part of the visual pathway, from the retina to the striate cortex. The pattern of visual field damage can indicate the location of the disorder. The case is presented here of an 8-year-old girl with congenital glaucoma. Initial perimetry appeared consistent with glaucomatous field loss; however, this evolved into a homonymous quadrantanopia, indicating the presence of a cerebral lesion as the cause. Computed tomography and magnetic resonance imaging scans detected a large middle cranial fossa arachnoid cyst. Postoperatively there was resolution of the visual field defects secondary to the arachnoid cyst. The pattern of field loss was pivotal in this patient's management. Attention must be paid when caring for the patient with a chronic disease to ensure that concurrent conditions are diagnosed.

Arachnoid Cysts↗

PubMed2003

Does a family history of glaucoma affect disease severity at the time of diagnosis?

PURPOSE: Progressive glaucomatous optic neuropathy is an asymptomatic process with an insidious onset. Patients who are aware of glaucomatous signs and who suspect that they may have the disease may present earlier. If a person has glaucoma, this may alert his or her other family members to seek assessment and thereby permit earlier diagnosis. The authors sought to determine whether glaucoma patients with a family history of the disease were younger and showed less evidence of glaucomatous optic neuropathy at diagnosis than glaucoma patients without a family history of the disease. PATIENTS AND METHODS: Family history of glaucoma, age at diagnosis, and visual field mean defect within 2 years after diagnosis were recorded in 292 patients with primary open-angle glaucoma. Results were analyzed to compare visual field loss with age and family history. RESULTS: At diagnosis, patients with a family history of glaucoma were younger than those without such a history (mean +/- SD, 58 +/- 12.7 years versus 63 +/- 10.8 years; = 3.68, P<0.001). Patients who were younger than 50 years at the time of diagnosis and had a positive family history were significantly less likely to have a worse visual field than those with a negative family history (OR = 0.3; 95% CI, 0.1-0.6; P<0.001), whereas those aged 50 years or older showed no such correlation (OR = 0.9; 95% CI, 0.7-1.3; P = 0.6). CONCLUSION: A family history of glaucoma was associated with a better visual field at diagnosis in patients younger than 50 years, but not in patients 50 years or older.

Adult↗

PubMed2002

Analysis of risk factors that may be associated with progression from ocular hypertension to primary open angle glaucoma.

BACKGROUND: As a multifactorial disease, glaucoma may be associated with pressure-dependent and pressure-independent factors. Ocular hypertension (OHT) may develop into primary open angle glaucoma (POAG) for many patients. Groups with OHT and POAG were compared for pressure-dependent and independent risk factors. A high prevalence of any factor(s) could indicate a contribution to progression from OHT to POAG. METHODS: A sample of patients with POAG (n = 438) and with OHT (n = 301) were selected from those attending a tertiary referral private glaucoma practice, and data were collected regarding age and intraocular pressure at the time of diagnosis, sex, family history of glaucoma, systemic hypertension, diabetes, Raynaud's phenomenon, migraine and myopia. RESULTS: After multivariate analysis, older age at time of diagnosis (chi(2)(5) = 73.89, P < 0.001), myopia (odds ratio [OR] = 1.5, 95% confidence interval [CI] 1.0-2.2; P < 0.05), a family history of glaucoma (OR = 1.6, 95% CI 1.1-2.3; P < 0.01) and a high intraocular pressure (chi(2)(4) = 16.96; P = 0.002) were found to be more prevalent among those with POAG. No other significant differences could be found between the two groups. CONCLUSION: Patients who have OHT may be at higher risk of developing POAG if they also have myopia, a family history of glaucoma or are of older age.

Adult↗