Temperature-dependent autoactivation associated with clinical variability of PDGFRB Asn666 substitutions

Ocular pterygium-digital keloid dysplasia (OPDKD) presents in childhood with ingrowth of vascularized connective tissue on the cornea leading to severely reduced vision. Later the patients develop keloids on digits but are otherwise healthy. The overgrowth in OPDKD affects body parts that typically have lower temperature than 37°C. We present evidence that OPDKD is associated with a temperature sensitive, activating substitution, p.(Asn666Tyr), in PDGFRB. Phosphorylation levels of PDGFRB and downstream targets were higher in OPDKD fibroblasts at 37°C but were further greatly increased at the average corneal temperature of 32°C. This suggests that the substitution cause significant constitutive autoactivation mainly at lower temperature. In contrast, a different substitution in the same codon, p.(Asn666Ser), is associated with Penttinen type of premature aging syndrome. This devastating condition is characterized by widespread tissue degeneration, including pronounced chronic ulcers and osteolytic resorption in distal limbs. In Penttinen syndrome fibroblasts, equal and high levels of phosphorylated PDGFRB was present at both 32°C and 37°C. This indicates that this substitution causes severe constitutive autoactivation of PDGFRB regardless of temperature. In line with this, most downstream targets were not affected by lower temperature. However, STAT1, important for tissue wasting, did show further increased phosphorylation at 32°C. Temperature-dependent autoactivation offers an explanation to the strikingly different clinical outcomes of substitutions in the Asn666 codon of PDGFRB.

A tyrosine kinase-activating variant Asn666Ser in PDGFRB causes a progeria-like condition in the severe end of Penttinen syndrome

Missense variants located to the "molecular brake" in the tyrosine kinase hinge region of platelet-derived growth factor receptor-β, encoded by PFGFRB, can cause Penttinen-type (Val665Ala) and Penttinen-like (Asn666His) premature ageing syndromes, as well as infantile myofibromatosis (Asn666Lys and Pro660Thr). We have found the same de novo PDGFRB c.1997A>G p.(Asn666Ser) variants in two patients with lipodystrophy, acro-osteolysis and severely reduced vision due to corneal neovascularisation, reminiscent of a severe form of Penttinen syndrome with more pronounced connective tissue destruction. In line with this phenotype, patient skin fibroblasts were prone to apoptosis. Both in patient fibroblasts and stably transduced HeLa and HEK293 cells, autophosphorylation of PDGFRβ was observed, as well as increased phosphorylation of downstream signalling proteins such as STAT1, PLCγ1, PTPN11/SHP2-Tyr580 and AKT. Phosphorylation of MAPK3 (ERK1) and PTPN11/SHP2-Tyr542 appeared unaffected. This suggests that this missense change not only weakens tyrosine kinase autoinhibition, but also influences substrate binding, as both PTPN11 tyrosines (Tyr542 and Tyr580) usually are phosphorylated upon PDGFR activation. Imatinib was a strong inhibitor of phosphorylation of all these targets, suggesting an option for precision medicine based treatment.

Correlation between observation task performance and visual acuity, contrast sensitivity and environmental light in a simulated maritime study

PURPOSE

To examine the relevance of visual acuity (VA) and index of contrast sensitivity (ICS) as predictors for visual observation task performance in a maritime environment.

METHODS

Sixty naval cadets were recruited to a study on observation tasks in a simulated maritime environment under three different light settings. Their ICS were computed based on contrast sensitivity (CS) data recorded by Optec 6500 and CSV-1000E CS tests. The correlation between object identification distance and VA/ICS was examined by stepwise linear regression.

RESULTS

The object detection distance was significantly correlated to the level of environmental light (p < 0.001), but not to the VA or ICS recorded in the test subjects. Female cadets had a significantly shorter target identification range than the male cadets.

CONCLUSION

Neither CS nor VA were found to be significantly correlated to observation task performance. This apparent absence of proven predictive value of visual parameters for observation tasks in a maritime environment may presumably be ascribed to the normal and uniform visual capacity in all our study subjects.

Contrast sensitivity measured by two different test methods in healthy, young adults with normal visual acuity

PURPOSE

This study reports contrast sensitivity (CS) reference values obtained by two different test methods in a strictly selected population of healthy, young adults with normal uncorrected visual acuity. Based on these results, the index of contrast sensitivity (ICS) is calculated, aiming to establish ICS reference values for this population and to evaluate the possible usefulness of ICS as a tool to compare the degree of agreement between different CS test methods.

METHODS

Military recruits with best eye uncorrected visual acuity 0.00 LogMAR or better, normal colour vision and age 18-25 years were included in a study to record contrast sensitivity using Optec 6500 (FACT) at spatial frequencies of 1.5, 3, 6, 12 and 18 cpd in photopic and mesopic light and CSV-1000E at spatial frequencies of 3, 6, 12 and 18 cpd in photopic light. Index of contrast sensitivity was calculated based on data from the three tests, and the Bland-Altman technique was used to analyse the agreement between ICS obtained by the different test methods.

RESULTS

A total of 180 recruits were included. Contrast sensitivity frequency data for all tests were highly skewed with a marked ceiling effect for the photopic tests. The median ICS for Optec 6500 at 85 cd/m2 was -0.15 (95% percentile 0.45), compared with -0.00 (95% percentile 1.62) for Optec at 3 cd/m2 and 0.30 (95% percentile 1.20) FOR CSV-1000E. The mean difference between ICSFACT 85 and ICSCSV was -0.43 (95% CI -0.56 to -0.30, p<0.00) with limits of agreement (LoA) within -2.10 and 1.22. The regression line on the difference of average was near to zero (R2=0.03).

CONCLUSION

The results provide reference CS and ICS values in a young, adult population with normal visual acuity. The agreement between the photopic tests indicated that they may be used interchangeably. There was little agreement between the mesopic and photopic tests. The mesopic test seemed best suited to differentiate between candidates and may therefore possibly be useful for medical selection purposes.

Ocular pterygium--digital keloid dysplasia

We describe an adolescent Peruvian male with marked, aggressive ingrowth of conjunctiva (pterygium-like) over the cornea associated with keloid formation on his distal limbs. He has in addition camptodactyly of all fingers and to some extent of his toes, and unusual skin pigmentations. He resembles an earlier described family from Norway in which a mother and two children showed a similar combination of signs. We present the follow-up of the Norwegian family. The entity resembles the Penttinen syndrome but can be differentiated due to the early aging in the latter, which is lacking in the presently reported entity. We suggest naming this entity ocular pterygium-digital keloid dysplasia. The condition follows likely an autosomal dominant pattern of inheritance.

Matching fundus photographs of classmates. An informal competition to promote learning and practice of direct ophthalmoscopy among medical students

PURPOSE

To present a new approach for teaching direct ophthalmoscopy to medical students.

METHODS

At the University of Bergen, four consecutive classes of fourth-year medical students complete a required 9-week ophthalmology course every year. In the present project, one fundus photograph was taken of each student. The photographs were randomly numbered, printed on A4 glossy photo paper, and displayed on the classroom wall. Each student was given a form to fill in the fellow students' names matching the number of the fundus photographs. They were encouraged to practise direct ophthalmoscopy on their classmates outside formal teaching hours. At the end of the course, they returned the filled-in forms, and those with the highest number of correct matches between the fundus photographs and fellow students received a reward.

RESULTS

Between 2011 and 2013, 239 students completed their ophthalmology course. Of these, 220 students (92%) voluntarily participated in the project. The mean score was 70% correct matches between fundus photographs and fellow students (range 7 - 100%). The students' course evaluations were overall positive.

CONCLUSIONS

We recommend the use of peer fundus photographs in the context of a learning competition as a simple, inexpensive, and effective way to improve teaching of direct ophthalmoscopy.

Acute bacterial conjunctivitis

Acute bacterial conjunctivitis is the eye disease most commonly seen by general practitioners, and is estimated to represent approximately 1% of all consultations in primary care. This article gives a review of the epidemiology, aetiology, clinical picture, complications, differential diagnoses, in vitro examinations and therapy of acute bacterial conjunctivitis. Until now, topical antibacterial therapy has generally been preferred by both physicians and patients because this will usually shorten the course of the disease slightly and allow the early readmittance of children to their kindergarten or school. Recently, several reports from primary care have confirmed the well-known clinical experience that the disorder has an excellent prognosis with a high frequency of spontaneous remission. In accordance, an expectant attitude or delayed prescription policy are now frequently strongly recommended. However, these reports also emphasize the difficulty in making a correct clinical distinction between bacterial and viral conjunctivitis. The effect of a general non-prescription attitude on transmission rates of pathogens also remains to be clarified. This must be born in mind when deciding how these patients should be handled. The socioeconomic and medical pros and cons of different treatment policies are discussed, and a highly personal view on the optimal handling strategy for these patients is also presented.

The influence of donor age and cause of death on corneal endothelial cell density

PURPOSE

To evaluate the joint effects of donor age and cause of death on the endothelial cell density of fresh human corneas.

METHODS

The corneal endothelial cell density of 946 eyes from 946 donors was analysed. The donors were divided into three age groups: group 1 comprised those aged 50 years and less; group 2 those aged 51-75 years, and group 3 those aged over 75 years. They were also grouped according to the cause of death: group A included those who had died of cancer; group B those who had died of acute myocardial infarction, pulmonary embolism or intracerebral haemorrhage, and group C those who had died as a result of other diseases.

RESULTS

There was a statistically significant negative correlation between donor age and mean corneal endothelial cell density, which was 2868 +/- 309 cells/mm(2) in group 1, 2716 +/- 335 cells/mm(2) in group 2, and 2670 +/- 368 cells/mm(2) in group 3. Among the various causes of death, the mean endothelial cell density was 2677 +/- 343 cells/mm(2) in group A, 2741 +/- 367 cells/mm(2) in group B, and 2713 +/- 337 cells/mm(2) in group C. The endothelial cell density was significantly lower in group A than in group B (p = 0.02). When the donors in the oldest age group (group 3) were analysed according to the various causes of death, the difference between group A (2603 +/- 342 cells/mm(2)) and group B (2729 +/- 338 cells/mm(2)) was even more significant (p = 0.0067).

CONCLUSION

Longlasting, severe diseases like cancer, leading to cachexia and catabolism, reduce the number of endothelial cells to a greater degree than diseases that cause a more rapid death. This negative effect of cancer on endothelial cell density is aggravated by the general decline in endothelial cell density with advancing age.

Nordic research in ophthalmology

Nordic ophthalmologists and vision scientists are active in many fields of eye research. This is most evident at the biannual Nordic Congress of Ophthalmology, most recently held in Malmö in June 2004. The authors here review some of the research in vision and ophthalmology presented at this meeting or published recently by Nordic scientists. This paper does not represent a comprehensive review of all Nordic research in the field, but attempts to give an overview of some of the activities underway in eye research in this part of the world.

[Can work-related eye injuries be avoided?]

BACKGROUND

The eyes are among the organs most frequently hurt in occupational injuries. The characteristics of eye injuries were studied in order to suggest preventive measures.

MATERIAL AND METHODS

Analyses were performed on work-related eye injuries reported to the Norwegian Injury Surveillance System from a selection of emergency centres during the period 1990-2002, and on injuries reported by employers to the National Insurance Administration 1998-2001.

RESULTS

The occurrence of injuries was stable over the period. Men sustained 94.4% of the injuries registered in injury surveillance system. The highest incidence was among those 20 to 24 years of age. Metal cutters and tools for polishing were involved in 25.7% of cases. Analyses of the injuries reported to the National Insurance Administration showed an odds ratio of 8.8 (95% CI 7.6-10.1) for injuries to workers in metal industry, 18.8 (95% CI 17.0-20.8) in automotive industry, and only 0.5 (95% CI 0.1-3.4) in oil refineries. Workers in oil refineries have a potentially hazardous work environment, but there, eye protection is mandatory.

INTERPRETATION

There was no decline in the incidence of work-related eye injuries from 1990 to 2002. Workers in metal industry have a high risk of injuries and employers should consider requiring the use of eye protection.

[Acute bacterial conjunctivitis]

Acute infectious conjunctivitis is the eye disease most commonly seen by general practitioners, and is estimated to represent 2-3% of their total number of consultations. The present paper gives a review of the epidemiology, etiology, clinical picture, complications, differential diagnoses and therapy of acute bacterial conjunctivitis. The condition has an excellent prognosis with a high frequency of spontaneous remission. However, topical antibacterial therapy should always be instituted, because this will shorten the course of the disease and reduce the risk of epidemic outbreaks, particularly in institutions for children.

[Ocular changes in Down syndrome]

BACKGROUND, MATERIAL AND METHODS

Down's syndrome is the most common cause of mental retardation with an incidence of about 1.5/1000 live births. Life expectancy and quality of life have improved substantially for this group over the last decades. The aim of this paper is to give an updated short survey of ocular changes present in Down's syndrome based on current international literature and the clinical experience of the authors.

RESULTS AND INTERPRETATION

Ocular problems are common, mostly refractive errors, poor accommodation, strabismus, cataract, and keratoconus. Accommodation deficit is present in a majority of individuals with Down's syndrome, also in children and young people. Bifocal or progressive glasses should therefore be prescribed liberally. Because of the high frequency of ocular pathology, all individuals with Down's syndrome should be enrolled in a continuous visual screening programme from birth. We suggest the following screening guidelines: first examination at one month of age, then at one year of age, at 2-3 years of age, at 5-6 years of age (school start), and thereafter every five years. In case of positive findings (e.g. refractive errors, poor accommodation, strabismus) the frequency of examination should be increased and determined individually by the responsible ophthalmologist.

Biometric measurements of the eyes in teenagers and young adults with Down syndrome

PURPOSE

To examine ocular biometric variables in subjects with Down syndrome.

METHODS

In a population-based study we have compared ocular biometric variables in a group of 47 individuals with Down syndrome (20.0+/-3.9 years) with 51 control subjects (21.0+/-4.6 years).

RESULTS

A thinner cornea (0.48+/-0.04 mm vs. 0.55+/-0.03 mm, p<0.001) and higher keratometry values (46.39+/-1.95 D vs. 43.41+/-1.40 D, p<0.001) were found in the Down syndrome group than in the control group. Oblique astigmatism was commonly found in the Down syndrome individuals, showing a strong right-left specificity (right eyes' axes in the 135 degrees -meridian, left eyes' axes in the 45 degrees -meridian). The lens was thinner (3.27+/-0.29 mm vs. 3.49+/-0.20 mm) and the calculated lens power was weaker (17.70+/-2.36 D vs. 19.48+/-1.24 D) in the Down syndrome group than in the control group (p<0.001 in both cases).

CONCLUSIONS

Thinning of the corneal stroma may account for the steeper cornea and the high frequency of astigmatism in Down syndrome due to lower corneal rigidity. It may also be of etiological importance to the increased incidence of keratoconus in Down syndrome.

Corneal grafting for keratoconus in mentally retarded patients

PURPOSE

To compare the results of penetrating and non-penetrating corneal grafting procedures in mentally retarded keratoconus patients.

METHODS

In the years 1974-2000 41 mentally retarded patients with keratoconus (33 with Down syndrome) were operated with corneal grafting. Mean age at operation was 36.7+/-10.8 years. Three different surgical procedures were used (no randomization): penetrating keratoplasty (n=16), lamellar keratoplasty (n=5) and epikeratophakia (n=20). In a retrospective study, the non-penetrating procedures (lamellar keratoplasty and epikeratophakia) were compared to the penetrating keratoplasties with regard to graft survival and frequency of serious complications. Mean follow-up time of all grafting procedures was 80+/-58 months.

RESULTS

All cases of serious complications (irreversible rejection, wound leakage or perforation) occurred in the penetrating keratoplasty group (p=0.0005). Older age at operation (p=0.011) adversely influenced the frequency of serious complications. Overall five-year survival was 74.9%. Graft survival was not related to surgical procedure, but rather to age at operation (poorer survival in older age, p=0.012) and degree of retardation (poorer survival in patients with more severe retardation, p=0.051).

CONCLUSIONS

Because of the safety and low frequency of complications, epikeratophakia is recommended as the grafting procedure of choice in the majority of mentally retarded with keratoconus. In selected cases (good cooperation, age < or =40 years, and a good peripheral corneal thickness) penetrating keratoplasty may be performed, which, if uncomplicated, often will give better functional/optical results.

Refractive development in children with Down's syndrome: a population based, longitudinal study

AIMS

To study the refractive development in children with Down's syndrome longitudinally.

METHODS

An unselected population of 60 children with Down's syndrome was followed with repeated retinoscopies in cycloplegia for 2 years or more (follow up 55 (SD 23) months). Accommodation was assessed with dynamic retinoscopy.

RESULTS

From longitudinal spherical equivalent values of the right eye, three main categories of refraction were defined: stable hypermetropia (<1.5 D difference between the first and last visit) (n=34), increasing hypermetropia ("hypermetropic shift"; >/=1.5 D difference) (n=11), and decreasing hypermetropia/development of myopia ("myopic shift"; >/=1.5 D difference) (n=9). Patients with anisometropia (n=6) were evaluated separately. In the stable hypermetropia group three sublevels were chosen: low (</=+2.0 D at the last visit), moderate (+2.25 to + 4.0 D), and high (>+4.0 D). An accommodation weakness was found in 55% of the children. Accommodation weakness was significantly less frequent in the stable, low grade hypermetropia group (22%) than in all the other groups (p=0.008). The frequency of astigmatism >/=1.0 D at the last visit was 57%, the direction of axis being predominantly "with the rule." All the eyes with oblique astigmatism had a side specific direction of axis; the right eyes belonging to the 135 degrees axis group and the left eyes to the 45 degrees axis group.

CONCLUSION

A stable, low grade hypermetropia was significantly correlated with a normal accommodation. Accommodation weakness may be of aetiological importance to the high frequency of refractive errors encountered in patients with Down's syndrome. A striking right-left specificity in the oblique astigmatic eyes suggests that mechanical factors on the cornea from the upward slanting palpebral fissures may be a major aetiological factor in the astigmatism.

Strabismus and binocular function in children with Down syndrome. A population-based, longitudinal study

PURPOSE

We have performed a population-based, longitudinal study on strabismus in children with Down syndrome. The aims of the study were to examine the frequency and type of strabismus, the age at onset, and the binocular potential.

METHODS

An unselected population of 60 children with Down syndrome born 1988-1999 was followed with repeated examinations. Mean follow-up time was 55+/-23 months (range 24--115). The alignment of the eyes was examined using Hirschberg corneal reflex test and cover test for near fixation. To evaluate binocular function, Titmus House Fly Test and Lang's stereo test were used.

RESULTS

Twenty-five patients (42%) had strabismus (21 esotropias, two exodeviations and two vertical deviations). Only one case of infantile esotropia was found, the other esotropias were acquired forms. The mean age at "onset" (e.g. when strabismus was first noticed) was 54+/-35 months. In the acquired esotropia group (n=20), 15 (75%) were associated with hypermetropia (mean spherical equivalent +4.3+/-1.7 D). Seventeen of the strabismic patients had an accommodation weakness. Eleven of the strabismus patients gave a clearly positive response to one or both stereotests.

CONCLUSIONS

The majority of the Down syndrome children with strabismus have an acquired esotropia and hence a potential for binocularity. Hypermetropia and accommodation weakness are probably important factors in esotropia in Down syndrome patients.

[Corneal transplantation]

The first successful corneal transplantation was done in 1906, when the corneas of a recently deceased boy were transferred to a man blinded by an alkali burn. Since then, improved equipment, microsurgical technique and better methods for treating postoperative complications have greatly improved the prognosis of corneal grafting. Immunological reactions are less frequently seen after keratoplasty than after other types of transplantation, and the graft is also directly accessible for immunosuppressive treatment. Penetrating keratoplasty accounts for more than 95% of all corneal transplantations in Norway, the other procedures being lamellar grafting and epikeratophakia. While keratitis and macula corneae previously were the main indications for keratoplasty, keratoconus is at present the most frequent indication. The prognosis is poorer in eyes with extensive vascularization, lacking sensibility, insufficient tear secretion and marked symblepharon. Due to shortage of suitable donor tissue, the waiting lists for this type of ocular surgery are increasing.

[Adverse effects of local use of beta-blockaders in glaucoma. A literature review and a survey of reports to the adverse drug reaction authority 1986-95]

The review is based on a survey of studies on adverse reactions related to topical administration of beta-blockers for glaucoma. Locally applied beta-blocking agents are partially resorbed from the nasal mucosa. Concentrations which give rise to systemic effects occur invariably. Several reports exist of congestive heart failure, arrhythmias, severe respiratory symptoms, depression, hallucinations and confusion provoked by topical use of beta-blockers, especially timolol. It is impossible to estimate from the literature how often the various adverse effects occur. One has the impression, however, that adverse effects in the pulmonary and central nervous systems have not been fully considered. Between 1986 and 1995 the Norwegian Medicines Control Authority received reports on adverse reactions related to topical use of beta-blockers in 17 patients. Six of these patients had cardiovascular and four of them severe respiratory symptoms. The latter group also included three fatal cases. The adverse effects seem to occur most frequently in the elderly, and it has been suggested that timolol should not be used in elderly people. Adverse effects related to treatment with topical beta-blockers are probably underreported in Norway.

Retrobulbar anesthesia with and without adrenaline in extracapsular cataract surgery. A prospective, randomized, double-blind study

Seventy-five patients with senile cataract underwent a planned extracapsular cataract extraction. They were randomly divided into two groups, receiving retrobulbar anesthesia (4 ml lidocaine 2% and 250 IU hyaluronidase) with or without adrenaline. Patients in the adrenaline group had the lowest mean intraocular pressure after the retrobulbar injection (p < 0.02) and they required a shorter time of digital bulbar massage to reduce tension before surgery (p < 0.01). They also appeared to have a deeper anterior chamber during the first part of surgery, although the difference was not statistically significant. The duration of postoperative analgesia was significantly prolonged in patients receiving adrenaline. Different mechanisms explaining the effects of adrenaline in retrobulbar anesthesia are discussed.

Do we operate too many cataracts? The referred cataract patients' own appraisal of their need for surgery

A questionnaire was sent to 379 patients referred for cataract extraction, asking them to assess their visual disability and their need for surgery. Two hundred and seventy-nine patients (73.6%) answered the questionnaire, this group being representative for the 379 patients regarding all relevant variables. The patient's answers were analyzed in relation to data extracted from their referral notes (visual acuity, monocular pseudophakia, age, sex, place of residence, referring ophthalmologist). The overall level of self-reported visual problems and need for cataract surgery were significantly correlated to a reduced best-eye visual acuity, although the correlation factor was low. A similar correlation between the subjective need for surgery and a worst-eye visual acuity < or = 6/24 was also found. Forty-seven patients (16.9%) answered that cataract surgery was not needed for the time being, and this attitude was not significantly correlated to the visual acuity, provided the acuity was > or = 6/24 in the best eye and > or = 6/36 in the worst eye. One hundred and twenty patients (43.0%) felt that their visual disability was so severe that they had to be operated within 1 month and 67 patients (24.0%) within 3 months, while 45 patients (16.1%) felt that surgery could be postponed for at least 6 months. Age, sex, place of residence and the presence of monocular pseudophakia were not found to significantly influence the level of self-reported visual problems. Only 18.3% preferred to be treated as out-patients.

Corneal astigmatism. The effect of transverse corneal incisions

The results of transverse or combined transverse and radial keratotomy in eyes with idiopathic corneal astigmatism (N = 11), astigmatism+myopia (N = 9) or early stages of keratoconus (N = 6) are presented. The corneal astigmatism was reduced in all our patients, the absolute reduction being significantly correlated to the degree of preoperative astigmatism (p = 0.007). In the whole study group the mean relative reduction of the corneal astigmatism was 52.7%. In eyes without keratoconus the astigmatism recorded at the last follow-up visit was very similar to that measured a few days after surgery, while greater changes occurred in the keratoconus group.

The refractive error after implantation of a posterior chamber intraocular lens. The accuracy of IOL power calculation in a hospital practice

The study included 188 patients, in which a posterior chamber intraocular lens was implanted after extracapsular cataract extraction. After modifications of the intraocular lens constants (SRK formula and SRK II formula) and correction of the axial length measurements (Colenbrander-Hoffer formula) had been made, the mean differences between the actual postoperative spherical equivalent and that predicted by the three formulas were -0.23D, -0.22D and -0.46D, respectively. More than +/-1.0D deviation from the predicted postoperative refraction occurred in about one-third of the cases. Inter-observed discrepancy regarding the accuracy of the preoperative measurement of the ocular axis length is suggested to be the main cause of unpredicted postoperative refractive errors.

Transverse keratotomy in postkeratoplasty astigmatism

Transverse relaxing incisions were made in 12 eyes with a mean corneal astigmatism of 10.7D following penetrating keratoplasty. A few days later the mean graft astigmatism had been reduced to 5.5D (p = 0.0022), the reduction being significantly correlated to the degree of astigmatism before the keratotomy was done (p = 0.0044). Thereafter the corneal contour remained fairly stable through a mean follow-up period of 28.1 months, although a tendency towards a further reduction of the astigmatism was indicated. The mean corrected visual acuity improved from 0.5 before the keratotomy to 0.7 at the last control visit (p = 0.0117).

Suture adjustment in penetrating keratoplasty

Postoperative adjustment of a single running penetrating corneal graft suture was done in 19 patients (22 adjustments). The short-term effect of this procedure was a mean reduction of corneal astigmatism of 4.39D (p < 0.0001). Thereafter, the corneal contour was fairly stable, provided that the running suture remained intact and tight. Localized loosening of the graft suture significantly increased the corneal astigmatism. Following removal of the graft suture no statistically significant mean change of corneal astigmatism was found. However, patients with a previously intact running suture tended to show increased astigmatism, while those with a previous localized suture loosening usually showed a decreased astigmatism after suture removal. The main benefit of suture adjustment is apparently the rapid and fairly stable reduction of postkeratoplasty astigmatism usually obtained, but unfortunately this effect seems chiefly to exist only as long as the graft suture remains intact and tight.

Retrobulbar anesthesia with and without hyaluronidase in extracapsular cataract surgery. A prospective, randomized, double-blind study

Eighty patients with senile cataract were subjected to a planned extracapsular cataract extraction (ECCE) with implantation of a posterior chamber intraocular lens. Retrobulbar anesthesia was administered by injection of 4 mg lidocaine 2% with adrenalin. In 40 patients 150 I.U. hyaluronidase (Kinetin) was added to the anesthesia. The hyaluronidase group had a significantly lower frequency of iris prolapse, and deeper anterior chamber, both before and after expression of the lens nucleus. Possible mechanisms explaining the beneficial effect of hyaluronidase in extracapsular cataract surgery are discussed.

Epikeratophakia for keratoconus in mentally retarded patients. The use of fresh, free-hand made lamellar grafts

Epikeratophakia for keratoconus was done in 11 mentally retarded patients, using fresh, free-hand made lamellar grafts. The mean follow-up period was 31.5 months. The grafts remained clear and well adapted in 7 cases (63.6%). Necrosis of the lower part of the graft occurred in 3 eyes (27.3%), and was probably caused by persisting epithelial defects. Only one of these grafts had to be removed. Despite concurrent eye diseases, such as cataract and possible amblyopia, an improved overall visual function was reported in 5 of the 11 patients (45.5%). No vision-threatening complications related to the epikeratophakia surgery was found.

Trabeculectomy and gelatin implants. A retrospective, long-term follow-up study

In a retrospective follow-up study including 60 eyes with simple or capsular glaucoma, the results obtained by using a gelatin implant under the scleral flap during trabeculectomy were compared with those obtained without such implants. One month postoperatively the mean IOP was significantly lower in the gelatin group than in the control group (15.0 mmHg and 17.9 mmHg, respectively) (p = 0.024). At the long-term follow-up, however, the mean IOP in the two groups were very similar (13.6 mmHg and 14.8 mmHg, respectively).

Epikeratophakia for keratoconus. Long-term results using fresh, free-hand made lamellar grafts

Epikeratophakia using fresh, free-hand made corneal grafts was done in 16 patients with keratoconus. The follow-up period averaged 27.8 months (range 13-45 months). A significant improvement of visual acuity was obtained (p = 0.002), and 14 of the 16 eyes (87.5%) achieved a corrected visual acuity greater than or equal to 6/12. The spherical equivalent and the cylindrical refractive error were reduced (p less than 0.05), and a significant flattening of the central corneal curvature was obtained (p less than 0.002). The mean postoperative central corneal astigmatism was 4.25 D. Postoperatively, the mean central corneal thickness was 0.670 mm, and the mean central thickness of the epithelialized graft was 0.336 mm. Six patients reported some postoperative glare or blurring of vision, despite a visual acuity greater than or equal to 6/9 on the Snellen chart. No significant subjective or objective changes were noticed after the 6-month postoperative follow-up visit.

The central corneal thickness in keratoconjunctivitis sicca

The central corneal thickness of 17 patients with keratoconjunctivitis sicca was compared with the thickness recorded in a control group of 105 subjects with healthy eyes. A moderate, but highly statistically significant central corneal thinning was found in the keratoconjunctivitis sicca group. The possible etiology and clinical importance of this finding is briefly discussed.

Multiple-dose, dose-response relationship for the topical carbonic anhydrase inhibitor MK-927

The multiple-dose, dose-response curve of MK-927 was studied in a five-center, double-masked, randomized, placebo-controlled, parallel study of 2%, 1%, and 0.5% MK-927 in 76 patients with bilateral primary open angle glaucoma or ocular hypertension and intraocular pressure greater than 24 mm Hg following washout of ocular hypotensive medications. Patients received doses at 8 AM and 8 PM for 14 days, and parallel 12-hour intraocular pressure curves were performed prestudy and on day 14, with 4-hour curves on days 1 and 4. There was a significant dose-response relationship, with 0.5% MK-927 twice daily being a minimal-effect dose. Both 1% and 2% MK-927 were active through 12 hours postdose, and peak mean percent decrease in pressure at 2 hours postdose was 18.6% and 20.6%, respectively.

Keratoprosthesis. II. Results obtained after implantation of 27 dismountable two-piece prostheses. A retrospective, follow-up study

During the years 1974-1987 a total of 27 two-piece keratoprostheses were implanted in 25 eyes of 22 different patients with bilateral blinding anterior segment disease with no possibility for a successful corneal transplantation. The prosthesis design and the surgical procedures used are described. The healing in and fixation of the prostheses were initially good in all cases, but 9 prostheses were lost or removed because of complications during the postoperative period of observation. The prosthesis retention time was significantly longer than that earlier achieved by the use of a one-piece prosthesis. In 18 of 27 cases a visual acuity of 6/60 or better was obtained. Postoperative complications included necrosis of the tissues covering and supporting the prosthesis, infection around the prosthesis, overgrowth of the surrounding tissues and the development of dense retroprosthetic membranes. Despite the obvious risks, keratoprosthesis surgery in a small number of patients with severe corneal disease represents the only potential hope for a visual rehabilitation, and should therefore be considered.

Keratoprosthesis. I. Results obtained after implantation of 12 one-piece prostheses. A retrospective, follow-up study

A total of 12 one-piece keratoprostheses were implanted in 6 eyes of 6 different patients with bilateral blinding, severe corneal disease with no possibility for a successful corneal transplantation. The prosthesis and the surgical procedure used are described. The short-term results were good, with 4 of the 6 patients obtaining a substantial visual improvement. In the remaining 2 patients preexisting pathology in the posterior segment of the eye was strongly suspected. However, the long-term complication rate was high, the chief problems being tissue necrosis around the prosthesis with eventual prosthesis loss and the development of retroprosthetic membranes. Repeated replacements of keratoprostheses extruded or removed because of complications were possible with restoration of the vision obtained after the first implantation.

Twelve-hour IOP control obtained by a single dose of timolol/pilocarpine combination eye drops

The 12 h IOP control achieved by a single application of a newly developed ophthalmic solution containing 0.5% timolol and 2% resp. 4% pilocarpine was compared with that obtained by 1 dose of timolol 0.5% alone in 33 patients with manifest open angle glaucoma or ocular hypertension. The combined solutions gave a significantly better 12 h IOP control, evidenced by both a reduced mean diurnal IOP and a decreased frequency of larger pressure peaks.

The prognosis of patients with hysterical visual impairment

During the period 1962-1986, 54 patients received the diagnosis hysterical visual impairment, i.e. 1 out of every 631 patients admitted to our department. Isolated visual acuity impairment was the most common symptom, followed by combined visual acuity impairment and visual field constriction, whereas isolated visual field constriction occurred most infrequently. The mean age of the patients in the first group was significantly lower than that of the patients in the latter group. A questionnaire sent to all patients in 1987 was answered by 41 patients. Twenty-one of these (51%) felt that their visual function now was good, whereas 20 (49%) claimed that their visual function was still poor. Nine patients (22%) were disabled because of their visual problems. Twenty-nine of the patients who answered the questionnaire were re-examined. Sixteen of these (55%) still showed visual impairment at the follow-up, while 13 (45%) showed complete disappearance of visual complaints. The younger patients appeared to have a better prognosis than the older ones.

A comparison between acyclovir and trifluorothymidine ophthalmic ointment in the treatment of epithelial dendritic keratitis. A double blind, randomized parallel group trial

This report presents the results of a double blind randomized study comprising 50 patients with epithelial herpes simplex keratitis. Twenty-five patients received 3% acyclovir ophthalmic ointment, the other 25 patients 2% trifluorothymidine (TFT) ophthalmic ointment. The mean duration of treatment in the 2 study groups before healing of the epithelial ulceration was obtained was 6.7 days and 5.9 days, respectively (no statistically significant difference). Two patient (8%) in the acyclovir group and 1 patient (4%) in the TFT group failed to heal within 14 days of treatment. No clinically significant adverse effects were recorded.

Timolol/pilocarpine combination eye drops in open angle glaucoma and in ocular hypertension. A controlled randomized study

The effect of a newly developed ophthalmic solution containing both 0.5% timolol and 2% resp. 4% pilocarpine was compared with that of timolol 0.5% eye drops alone in 93 patients with manifest simple or capsular glaucoma or ocular hypertension. The medications were administered twice daily. The absolute additive effect of pilocarpine was small, although the combined solutions caused a statistically significantly greater reduction of the intraocular pressure than that achieved by timolol alone. This additional effect appeared to last at least 12 h. The effect of the test solutions containing 2% resp. 4% pilocarpine was very similar. Apart from the well-known effects of the pilocarpine-induced miosis, the combined test medications were generally well tolerated.

Prognostic factors in the development of manifest open angle glaucoma. A long-term follow-up study of hypertensive and normotensive eyes

Ninety-three patients, who during a mass screening for glaucoma in 1962-63 attended a thorough ophthalmological examination, were re-examined in 1980-82. At the mass screening 42 patients had IOP greater than or equal to 21 mmHg in at least 1 eye, but none of the 93 patients had glaucomatous optic disc excavations or visual field defects. At the re-examination, 28 patients (30.1%) had developed manifest open angle glaucoma in at least 1 eye. This development was significantly correlated to the height of the IOP, both at the mass screening, during the period of observation and at the follow-up study (P less than 0.05-P less than 0.002). A reduced outflow facility measured at the mass screening was also significantly associated with the later development of manifest glaucomatous damage (P less than 0.05-P less than 0.01). In addition, fibrillopathy (pseudoexfoliation), manifest glaucoma in the 'fellow eye' and a positive family history for glaucoma were found to be important risk factors.

Deposits on hydrophilic 'bandage' lenses. A scanning electronmicroscopic and x-ray microanalytic study

Scanning electronmicroscopy of 34 continuously worn Sauflon PW 'bandage' lenses showed an initial deposition of cellular debris, followed by an increasing, general, non-penetrating, organic coating, particularly on the anterior lens surface. No microorganisms were found. X-ray microanalysis of the 34 Sauflon PW lenses as well as 11 daily worn Hydroflex m lenses showed that elements may be added to or 'washed out' from the lenses during storage before preparation for microscopy. The elements obtained were constituents of both normal tear fluid and lens storage solutions. Only sulphur appeared firmly bound in the deposits, probably as sulphur-containing macromolecules of ocular mucus. Calcium was only detected in a few cases.

Hydrophilic contact lenses in corneal disorders

Hydrophilic 'bandage' lenses were fitted in 107 patients with corneal disorders not satisfactorily responding to conventional medical treatment. An over-all beneficial effect on both ocular discomfort, visual acuity and corneal disorder was found (P less than 0.002). Regarding each group separately only patients with bullous keratopathy and those with corneal ulcers achieved a significant reduction of ocular discomfort (P less than 0.002) and a significant improvement of visual acuity (P less than 0.05 - P less than 0.01). In bullous keratopathy corneal oedema was significantly reduced by concomitant use of contact lenses and 5% NaCl eye drops (P less than 0.01). Significant improvement of corneal disorder occurred in patients with corneal ulcers and in those with corneal lacerations (P less than 0.002 and P less than 0.01, respectively). Complications included corneal vascularization (7.5%) and keratitis/keratoconjunctivitis (5.6%). Prophylactic use of topical antibiotics appeared necessary only in dry eye disease.

The fluid content of hydrophilic contact lenses on the eye

Hydroflex m, Hydroflex 72 and Sauflon PW lenses were tested (declared fluid content 38.4%, 72% and 79%, respectively). At room temperature in vitro the mean fluid content of Hydroflex m and Sauflon PW was significantly higher than declared (P less than 0.002), but this might be due to insufficient blotting of the lens surface. The mean fluid content of Hydroflex 72 was about 2.5% lower than declared (P less than 0.002). During wear the fluid content of Hydroflex m did not differ significantly from the in vitro recordings at room temperature, while the fluid content of worn Hydroflex 72 and Sauflon PW was about 2% lower than in vitro (P less than 0.002). This difference was mainly due to the greater temperature susceptibility of these lens materials. Apart from a slight decrease during the first few h after insertion (P less than 0.05), the fluid content of the lenses was not significantly influenced by the duration of wear. The mean contact lens surface temperature during wear was 30.7 degrees C.

Light-induced release of protoporphyrin, but not of zinc protoporphyrin, from erythrocytes in a patient with greatly elevated erythrocyte protoporphyrin

A patient with greatly increased erythrocyte protoporphyrin, but normal porphyrins in urine and feces, is described. The patient later developed a malignant lymphoma, and the reason why she accumulated protoporphyrin in her erythrocytes is not known. The protoporphyrin in the erythrocytes consisted of two types of protoporphyrin, free protoporphyrin (30%) and zinc protoporphyrin (70%). Upon irradiation of erythrocytes in the absence of albumin, protoporphyrin and zinc protoporphyrin, which were both bound to hemoglobin, were released. In contrast, when the irradiation was carried out in the presence of albumin, the photohemolysis was negligible, and there was release of free protoporphyrin, but not of zinc protoporphyrin, from the erythrocytes. In vivo albumin is present in the plasma and the results may help to explain why patients with erythropoietic protoporphyria (erythrocytes containing free protoporphyrin) are photosensitive, whereas patients with lead intoxication and iron deficiency (erythrocytes containing zinc protoporphyrin) are not.