Two different principles were studied. 1st - statistical analysis techniques were used to obtain medical results from a patient population. 2nd - the patient population was used to study the statistical analysis techniques. Medical conclusions: latanoprost and timolol treatment showed a statistically significant and clinically useful mean IOP-reduction in a typical worldwide clinical trial population. Latanoprost reduced the IOP 1.6 mm Hg more than timolol. The IOP-reduction was maintained with timolol and slightly enforced with latanoprost up to 6 months of treatment. The mean IOP-reduction was maintained during 2 years of latanoprost treatment. The overall risk of withdrawal due to insufficient IOP-reduction with latanoprost was 8%. The statistical methodological issues are of a general and reoccurring character in trial design of the IOP-reduction: should the statistical hypothesis testing be based on the mean intraocular pressure (IOP) or the proportion of patients who reach a specific IOP level, should the estimate of the IOP or IOP-reduction be based on single eyes, mean of bilaterally eligible and identically treated eyes or the difference between an eye with active treatment and a placebo treated contralateral eye, and is mean of replicated recordings useful? Statistical methodological conclusions: the most effective response variable varies with the selected patient population. Therefore, the trial design process should include a comparison of the variability, test power and required sample size for the possible response variables in a sample of the target population. At minimum a statistical consideration should be done.

In a prospective population-based study in Stockholm County, 1998-2000, the incidence of retinopathy of prematurity (ROP) was investigated and was found to be 36% in prematurely-born infants with a birth weight of ≤ 1500 grams. Compared to a study performed ten years ago, the overall incidence was unchanged, but was reduced in “mature” infants and increased in immature ones. The incidence of ROP was 25% in infants with a gestational age of ≤ 32 weeks at birth. The main risk factors for ROP were the gestational age at birth, followed by the birth weight. Current guidelines for ROP screening in Sweden were modified. A 10-year follow-up study of the ophthalmological findings in prematurely-born children, previously included in a prospective population-based incidence study of ROP, was performed. The children were compared with full-term ones. Prematurely-born children ran a four times higher risk of refractive errors than full-term ones. The cryotreated children had the highest risk, but those without ROP also had more refractive errors than the full-terms. Within the group of prematurely-born children, the cryotreated ones had the highest prevalence of myopia, astigmatism and anisometropia, but no difference was found regarding hypermetropia. The visual acuity of prematurely-born children was poorer than that of the full-terms. The cryotreated children and those with neurological complications had the most marked reduction, but the children without ROP and neurological findings also had a poorer visual outcome than the full-terms. The prevalence of visual impairment was 1.8% among the prematurely-born children, and was due to ROP in half the cases and cerebral lesions in the others. The cryotreated children had constricted peripheral visual fields compared to the untreated prematurely-born and full-term children. The central visual fields tended to be reduced in the prematurely-born children compared to the full-terms, but no difference was observed within the preterm group.

A high frequency of retinitis pigmentosa (RP) is found in Northern Sweden. In an inventory of autosomal recessive RP patients in Västerbotten County, a great number of cases with a unique phenotype was noticed, denoted Bothnia Dystrophy (BD). The aim of the study was to describe the phenotype, to determine the chromosomal location, and to identify the gene. Patients typically show night blindness from early childhood. Symptoms of defect macular function with a decrease of visual acuity can appear in early adulthood. The retinal fundus shows irregular white spots in a central, and parafoveal pattern along the arcades. Centrally areolar maculopathy develops and round circular atrophies are observed in the periphery. The disease was shown to be associated with a missense mutation in the RLBP1 gene resulting in an amino acid substitution (R234W) in the cellular retinaldehyde-binding protein (CRALBP). The R234W mutation was found in a homozygous state in 61 patients affected with BD. Ten patients were heterozygous for the R234W mutation, and presented a similar phenotype. No additional mutations in the coding sequence or exon-intron junctions were found. CRALBP is localised in retinal pigment epithelium (RPE), and Müller cells of the retina. In the RPE, CRALBP functions as a carrier protein for endogenous retinoids. Dark adaptometry and electrophysiologic testing showed an initial loss of rod function followed by a progressive reduction of the cone responses in older ages. A compromised rod function, dysfunction of the Müller cells, and indications of a disturbed function of the inner retina were found. With prolonged dark adaptation, a gradual increase in retinal sensitivity to light and an improvement of the ERG components occurred. The findings indicate a prolonged synthesis of photopigments, retardation of the visual process in the retinal pigment epithelium and a loss of retinal cells probably starting at a relative early age in BD. To evaluate the subjective visual function in BD patients, a battery of objective tests of visual function and composite score of the 25-item NEI-Visual Function Questionnaire (VFQ-25) were analyzed. We found that weighted distance logMAR visual acuity (WVA), had the strongest association with subjective visual function, and that there was a considerable loss of subjective and objective visual function with increasing age in BD patients. The prevalence of BD is as high as 1:3600 in Västerbotten County. The possibility that recycling of retinoids localized in the RPE might be impaired in BD might give future therapeutic possibilities. Due to the large and clinically well-characterized set of patients with this disease, they constitute a suitable study group.

<p>Glaucoma is a common disease in the elderly population. Open-angle glaucoma (OAG) is the predominant form of glaucoma. Chronic simple glaucoma and capsular glaucoma, characterized by the occurrence of pseudoexfoliation in the anterior eye segment, are the most frequent types of OAG. The purpose of the present thesis was to study the epidemiology of OAG in the municipality of Tierp, whose population has a high exposure to pseudoexfoliation.</p><p>In a case-finding study, the prevalence of known cases of OAG by December 31, 1983 was estimated to 1.4% in people ≥45 years of age. Sixty-three percent of all cases had capsular glaucoma. Patients with advanced glaucoma were older, had had the disease for longer, had higher mean initial intraocular pressure, and had more extensive visual field defects at the time of diagnosis.</p><p>A population survey of people 65–74 years of age was conducted in 1984–86. The prevalence of OAG was 5.3%. Pseudoexfoliation was found in 17%, being more common in females. Pseudoexfoliation was associated with OAG only in people previously diagnosed with the disease (odds ratio = 16). In cases detected at the survey, an intraocular pressure ≥20 mmHg was a serious risk factor of having OAG (odds ratio = 9.7).</p><p>In a 5-year follow-up study of participants in the population survey, increased intraocular pressure and pseudoexfoliation were recognized as independent risk factors for the development of OAG (standardized risk ratios = 3.4 and 9.8, respectively). Interaction between increased intraocular pressure and pseudoexfoliation was indicated. By May 2006, the incidence of OAG was estimated to 7.1 per 1,000 person-years. The incidence of capsular glaucoma was more than twice that of chronic simple glaucoma.</p><p>The prevalence and incidence of OAG was higher than that reported from other studies conducted on Caucasian populations. The probable explanation for this finding is exposure to pseudoexfoliation.</p>

Glaucoma is a common disease in the elderly population. Open-angle glaucoma (OAG) is the predominant form of glaucoma. Chronic simple glaucoma and capsular glaucoma, characterized by the occurrence of pseudoexfoliation in the anterior eye segment, are the most frequent types of OAG. The purpose of the present thesis was to study the epidemiology of OAG in the municipality of Tierp, whose population has a high exposure to pseudoexfoliation. In a case-finding study, the prevalence of known cases of OAG by December 31, 1983 was estimated to 1.4% in people ≥45 years of age. Sixty-three percent of all cases had capsular glaucoma. Patients with advanced glaucoma were older, had had the disease for longer, had higher mean initial intraocular pressure, and had more extensive visual field defects at the time of diagnosis. A population survey of people 65–74 years of age was conducted in 1984–86. The prevalence of OAG was 5.3%. Pseudoexfoliation was found in 17%, being more common in females. Pseudoexfoliation was associated with OAG only in people previously diagnosed with the disease (odds ratio = 16). In cases detected at the survey, an intraocular pressure ≥20 mmHg was a serious risk factor of having OAG (odds ratio = 9.7). In a 5-year follow-up study of participants in the population survey, increased intraocular pressure and pseudoexfoliation were recognized as independent risk factors for the development of OAG (standardized risk ratios = 3.4 and 9.8, respectively). Interaction between increased intraocular pressure and pseudoexfoliation was indicated. By May 2006, the incidence of OAG was estimated to 7.1 per 1,000 person-years. The incidence of capsular glaucoma was more than twice that of chronic simple glaucoma. The prevalence and incidence of OAG was higher than that reported from other studies conducted on Caucasian populations. The probable explanation for this finding is exposure to pseudoexfoliation.