Optical coherence tomography (OCT) is a technique in which cross-sectional images from intraocular tissue can be obtained. The quantitative and qualitative examinations are used for evaluating retinal diseases. Conventional OCT (Stratus) is mainly used, but the new Spectral domain (Cirrus) OCT, which has improved technology, may provide more reliable measurements. The aim of the study was to collect normal values of macular thickness in children and adults and to evaluate the effect of age and/or gender, to compare measurement variability in healthy eyes and eyes with age-related macular degeneration (AMD), to compare Stratus and Cirrus OCT and to study the effect of cataract surgery on macula. Sixty-seven healthy adults and 56 children, 30 patients with AMD, 34 patients with diabetes and cataract and 35 healthy controls were included. The quantitative maps in Stratus and Cirrus were used and manual correction of foveal location was evaluated. Qualitative OCT was compared to fluorescein angiography (FA) after cataract surgery. The mean values of macular thickness in Stratus OCT were 207µm in adults and 204 µm in children. The measurement variability was low. Macular thickness decreased with age in adults, but not in children. No correlation with gender was found. In eyes with wet AMD, there were small differences in measurement variability comparing Stratus and Cirrus OCT. After manual correction in Cirrus OCT, the coefficients of repeatability were improved to values close to the repeatability in normal eyes. Two thirds of the diabetic and half of the control eyes showed leakage on FA after cataract surgery. Qualitative OCT corresponded poorly to FA in diabetic eyes. A thicker macula, assessed with OCT, was often observed without any obvious effect on visual acuity.  OCT was as good as FA in revealing clinically relevant changes in macula after surgery, and was the technique recommended for follow-up.

Intraocular pressure (IOP) measurement is a routine procedure and a fundament in glaucoma care. Elevated IOP is the main risk factor for glaucoma, and to date, reduction of IOP is the only possible treatment. In a retrospective clinical material, the prevalence of open angle glaucoma was estimated on the west coast of Iceland. IOP measurement and optic nerve head examination were used to capture glaucoma suspects, within the compulsory ophthalmological examination for the prescription of eye glasses. The results were mainly in agreement with a recent prospective study in the same region. This indicated that retrospective data, under certain conditions, may contribute with useful information on the prevalence of glaucoma. However, normal tension glaucoma is underestimated if perimetry and/or fundus photography are not included in the examination. Three studies focused on the measurement of IOP. Goldmann applanation tonometry (GAT) is the standard method. GAT is affected by corneal properties, e.g. central corneal thickness (CCT) and corneal curvature (CC). Refractive surgery changes these properties. This has put focus on how corneal biomechanics translate into tonometric errors and stimulated the development of new methods. As a result, Pascal ® Dynamic Contour Tonometry (PDCT) and Icare® rebound tonometry have been introduced. A method under development by our research group is Applanation Resonance Tonometry (ART). It is based on resonance technology and estimates IOP from continuous measurement of force and contact area. Comparison of PDCT, Icare and GAT in a prospective study showed that the concordance to GAT was close to the limits set by the International Standard Organization (ISO) for PDCT, while Icare was outside the limits. To investigate if laser-assisted subepithelial keratectomy (LASEK) affects tonometry, a study was performed where measurements with GAT, PDCT and ART were obtained before, three and six months after LASEK. The hypothesis was that PDCT and ART would be less affected by LASEK than GAT. The results showed a statistically significant reduction of measured IOP three and six months after LASEK for all tonometry methods. Change in visual acuity and IOP between three and six months suggested a prolonged postoperative process. A servo-controlled prototype (ART servo) was developed. A study was undertaken to assess the agreement of ARTservo and a further developed v manual prototype (ART manual) with GAT. The study design was in accordance with the requirements of the ISO standard for tonometers. ARTmanual fulfilled the precision requirements of the ISO standard. ARTservo did not meet all the requirements of the standard at the highest pressure levels. Four tonometry methods, GAT, PDCT, Icare and ART, were investigated. None of them was independent of both CCT and CC. The inconsistencies in the results emphasize the importance of study design. A meta-analysis comprising healthy eyes (IOP ≤ 21 mmHg) in the three papers, revealed age as an important confounder. In summary, glaucoma prevalence in Iceland was investigated and the results indicated that a retrospective approach can contribute with meaningful information. ART and PDCT had a similar agreement to GAT. ART manual fulfilled the precision requirements set by the ISO-standard, ARTservo and PDCT were close, while Icare was distinctly outside the limits. All tonometry methods were affected by LASEK and no method was completely independent of corneal properties.

The extracellular matrix (ECM) offers a protective shelter for cells and provides signaling paths important for cell to cell communication. ECM consists of basement membranes (BM) and interstitial matrix. BMs provide mechanical support for parenchymal cells, influence cell proliferation, survival, migration and differentiation. They are also important for tissue integrity. Laminins (LM) are the major non-collagenous component of BMs. Cell-ECM interactions, mediated by receptors, are indispensable during embryonic development, wound healing, remodeling and homeostasis of tissues. The integrins are the major cell-adhesion receptors. The expression of alpha11 integrin chain in the cornea is of great interest, as it is part of the alpha11beta1 integrin receptor for collagen type I, the predominant component of the corneal stroma. The aims were to thoroughly characterize the ECM in the developing and adult human eye, with particular focus on the cornea, LM and alpha11 integrin chains, and to examine alpha11 integrin chain in an animal model of corneal wound healing and remodeling. Human fetal eyes, 9-20 weeks of gestation (wg), and adult human corneas with different diagnosis were treated for immunohistochemistry with specific antibodies against LM and alpha11 integrin chains. Normal and knockout (ko) mice were treated with laser surgery to create a deep wound in the corneal stroma. The wound healing process was followed at different time points. The cellular source of alpha11 integrin chain was studied in cell cultures. In the fetal eyes, the BM of the corneal epithelium, the Descemet’s membrane (DM) and the Bruch’s membrane each had their specific combinations of LM chains and time line of development, whereas the lens capsule and the internal limiting membrane showed constant LM chain patterns. The epithelial BMs of normal and diseased adult corneas contained similar LM chains. The normal morphology of the epithelial BM was altered in the different diseases, particularly when scarring was present. In the scarred keratoconus corneas there were excessive LM chains. The majority of keratoconus corneas also expressed extra LM chains in the DM. At 10-17 wg alpha11 integrin chain was present in the human corneal stroma, especially in the anterior portion, but it was scarce at 20 wg, in normal adult corneas and in Fuchs’ endothelial dystrophy. In contrast, it was increased in the anterior portion of the stroma in keratoconus corneas with scarring. Alpha11 integrin ko mice had a defective healing with subsequent thinner corneas. Alpha11 integrin expression correlated to the presence of alpha-smooth muscle actin in vivo as well as in vitro. The distinct spatial and temporal patterns of distribution for alpha11 integrin and each of the LM chains suggest that they play an important role in human ocular differentiation. The selectively affected LM composition and the novel expression of alpha11 integrin chain in scarred keratoconus corneas as well as the pathologic healing in ko mice, indicate that alpha11 integrin and LM chains also play an important role in the process of corneal healing, remodeling and scarring and might participate in the pathogenesis of corneal disease. This knowledge is of practical importance for future topical therapeutic agents capable of modulating the corneal wound healing processes.

Light and oxygen generate harmful reactive oxygen species (ROS) in the lens, causing biochemical changes that gradually disarrange the lens fibres resulting in light scattering and loss of transparency. In the healthy eye, this chronic exposure to oxidative stress may lead to age-related cataract. However, there are also some conditions that accelerate cataract formation, such as diabetes mellitus, in which increased glucose levels may contribute to increased generation of ROS. The superoxide dismutases (SOD) participate in the defence against ROS by catalysing the dismutation of superoxide radicals. The main SOD isoenzyme in the lens is copper-zinc superoxide dismutase (SOD1). The aim of this thesis was to explore if this antioxidant enzyme is important for the protection against age-related and diabetes-induced cataract development. Lenses from wild-type mice and mice lacking SOD1 were incubated in high levels of glucose in vitro and their transparency and damage evaluated daily. Also, the impact of nitric oxide was studied by adding a nitric oxide synthase inhibitor. Furthermore, in vivo cataract formation in relation to the oxidative status of the lens was evaluated in streptozotocin-induced diabetic mice as well as in non-diabetic mice of both genotypes. Finally, the spontaneous age-related cataract development was studied in both genotypes. In vitro, the SOD1 null lenses showed increased levels of superoxide radicals and developed dense nuclear lens opacities upon exposure to high levels of glucose. They also showed increased lens leakage of lactate dehydrogenase, reduced transport function across cell membranes, and increased water contents. However, the lens damage and cataract formation were eliminated when the synthesis of nitric oxide was inhibited. This indicates that both superoxide and nitric oxide have important roles in glucose-induced cataract development possibly through their reaction with each other which generates the highly reactive peroxynitrite. In vivo, both the SOD1 null and the wild-type mice showed cortical cataract changes after 8 weeks of diabetes, although the SOD1 null mice showed a more pronounced cataract formation than the wild-type mice in relation to the level of hyperglycaemia. As cataract formation was accentuated the lenses showed diminishing levels of glutathione but increasing amounts of protein carbonyls, suggesting a reduced lens antioxidant capacity as well as increased lens protein oxidation. Non-diabetic young (18 weeks of age) SOD1 null mice did not show any signs of cataract. At 1 year of age they had developed some cortical lens obscurity as compared to the wild-type mice which did not show equivalent changes until 2 years of age. The results presented in this thesis show that SOD1 null mice are more prone to develop diabetes-induced and age-related cataract than wild-type mice. The findings thus further endorse the importance of oxidative stress as a contributor to cataract development and indicate that both superoxide and nitric oxide may be damaging to the lens. I therefore conclude that the antioxidant enzyme SOD1 is important for the protection against cataract.

Background Cataract surgery is the most common surgical procedure carried out in the developed world and surgery volumes have increased considerably during the last decades. Various aspects of the surgical procedure, including surgical incision size and intraocular lens materials, have changed substantially, improving the safety and the quality of the outcome. Previous research has primarily focused on the visual function results with a short follow-up time. Long-term population-based studies, exceeding a few years, presenting visual functional results postoperatively, have not been published. Aims To determine the effects of cataract surgery on subjectively experienced visual function and visual acuity in a defined population, and compare the results between sub-groups, on a long-term basis. Methods In this prospective, population-based investigation, all patients with presenile and senile cataract (n=810), operated on during a one-year period (1997-98), at Umeå University Hospital were included. The frequency of cataract surgery at that time, was 5.2 per 1000 population studied. Visual acuity was tested and an eye examination was performed before surgery, 4-8 weeks postoperatively, and five and ten years after surgery. Subjective visual function was assessed using self-administered questionnaires (VF-14) at all occasions. Statistical evaluations comprised analyses of variance, Mann-Whitney U-test, chi-square test, multiple linear regression, a life-table calculation, and Cox’s proportional hazard model. Results Five years after cataract surgery, subjective and objective visual function remained stable in most patients. The most frequent cause of deterioration of visual acuity and decrease in VF-14 scores was agerelated macular degeneration (ARMD). Two thirds of the patients in the cohort were women. They were significantly older than the men and more often operated on both eyes. After adjustment for age and visual acuity, women cataract surgery patients assessed their visual function worse than men both before surgery and 4 months postoperatively. Five years after surgery these differences were no longer significant. At baseline, 13% of the patients were diabetics. At the five-year followup, subjective and objective visual function remained stable in most surviving diabetics, and the longitudinal visual function was not significantly worse compared with the non-diabetics. Ten years after surgery, 28% had received treatment for posterior capsular opacification (PCO). A significantly larger proportion of patients less than 65 years at surgery (37%) compared with those 65 years or older (20%) had been treated. Conclusions Most patients sustain their level of visual acuity and visual function also five and ten years after cataract surgery. Ocular co-morbidity, such as ARMD, is the major cause of longitudinally reduced visual function. Patients suffering from diabetes did not have a significantly worse visual function after five years. A surprisingly large proportion of patients had received treatment for PCO after ten years.

Background: Improved neonatal care has resulted in an increasing population of surviving infants. Neonatal morbidity in preterm infants is, however, high, and retinopathy of prematurity (ROP) is one of the major neonatal morbidities. Observations have suggested that ROP might have a different course in extremely preterm compared to more mature infants. Aims: To study the incidence, natural history and treatment of the disease, and the implications regarding screening recommendations for the population of extremely preterm infants. Methods: A national, population-based study of neonatal morbidity in infants born before 27 gestational weeks was performed in Sweden during 2004 to 2007. ROP screening started in the 5th postnatal week and continued until the retina was completely vascularized. Results: Of the 506 infants surviving until the first ROP examination, 73% developed ROP; 38% mild ROP and 35% severe ROP. Ninety-nine infants (20%) were treated. A log-linear relationship was found between severe ROP and gestational age (GA) at birth, and the risk of ROP was reduced by 50% for each week of increase in GA at birth (Paper I). Postmenstrual age (PMA) at onset of ROP was significantly related to GA at birth, as was the site of onset of ROP. ROP had a predilection to start in the nasal retina in the most immature infants. There were significant relations between PMA at onset of ROP and severity of ROP as well as between the site of onset of ROP and severe ROP (Paper III). The most immature infants had a higher risk of reaching treatment criteria for ROP, a higher risk of progression from ROP 3 to treatment criteria, and they reached these criteria at an earlier PMA than the less immature infants (Paper II). According to our results, the first examination can be postponed until a PMA of 31 weeks in infants born before 27 weeks of gestation, since onset of ROP 3 did not occur before this age, and criteria for treatment were not reached before 32 weeks. The majority of infants (75%) were treated during a limited period, i.e. before a PMA of 39 weeks (Paper IV).