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PubMed1987

Personality trends in keratoconus. An analysis.

Patients with keratoconus frequently are described as having peculiar personality characteristics, despite the lack of controlled studies in the ophthalmologic or psychiatric literature. We studied 109 subjects, using a standardized personality inventory (the Millon Clinical Multiaxial Inventory) that measures 20 personality scales-both normal and pathologic. Subjects were divided into three age-matched groups: (1) patients with keratoconus, (2) patients with other chronic eye diseases, and (3) normal controls. Results indicated that although chronic eye disease, including keratoconus, did have an impact on personality functioning in young and middle-aged adults, no specific complex of personality characteristics attributable to keratoconus could be identified. Patients with keratoconus differed from normal controls in much the same way as did patients with other chronic eye diseases, being less conforming and more passive-aggressive, paranoid, and hypomanic. They tended to more disorganized patterns of thinking and scored higher on substance abuse indicators. The influence of keratoconus on personality may be a function of the timing and nature of its onset in the context of the patient's psychosocial development.

Adolescent↗
PubMed1990

Development of keratoconus after contact lens wear. Patient characteristics.

A retrospective review of 398 eyes of 199 patients with keratoconus revealed 106 eyes of 53 patients with an association between contact lens wear and the development of keratoconus. The absence of keratoconus at the time of contact lens fitting was confirmed by slit-lamp examination, keratometry readings, and manifest refraction. Keratoconus was diagnosed after a mean of 12.2 years of contact lens wear. This group was compared with patients with sporadic keratoconus with either no history of contact lens wear or a history of contact lens wear after the diagnosis. They were older at the time of diagnosis, had central vs decentered cones, and had a tendency toward flatter corneal curvatures. We believe that these patients suggest that long-term contact lens wear is a factor that can lead to keratoconus.

Adolescent↗
PubMed1994

Lysosomal enzyme activities in conjunctival tissues of patients with keratoconus.

OBJECTIVE: To examine the lysosomal enzyme activities in the conjunctival tissues of patients with keratoconus. METHODS: Tissues collected from 11 patients with keratoconus, eight patients with senile cataract, three patients with Fuchs' corneal dystrophy, and 11 normal control subjects were processed for histochemical staining for two lysosomal hydrolases, acid esterase and acid phosphatase. RESULTS: The epithelium of all conjunctival specimens stained positively for the two enzymes. The staining in the conjunctival tissues of patients with keratoconus was more prominent than that seen in specimens from either normal control subjects or patients with other diseases. CONCLUSION: Our results suggest that the conjunctival epithelium may be altered in keratoconus. Elevation of lysosomal enzyme levels has been demonstrated in the epithelium of corneas with keratoconus, implicating a role of this layer in the disease. The conjunctival abnormality seems to corroborate the corneal epithelial theory. It also adds one dimension to the pathogenesis of keratoconus.

Acetylesterase↗
PubMed2002

Hereditary keratoconus-like keratopathy in Japanese wild mice mapped to mouse Chromosome 13.

Human keratoconus is a common corneal disease with non-inflammatory corneal ectasia, and a subset of this disease is heritable. In an effort to establish animal models for this disease, we discovered Japanese keratoconus (JKC) mice among Mishima molosinus (MSM) mice, an inbred strain of Japanese wild mice (Mus musculus molossinus). Typical phenotypic corneas of JKC mice are, like human keratoconus, conical in shape, although the corneas were often associated with a red punctum at the tip. In contrast to human keratoconus, histological examination revealed the inflammatory changes such as infiltration of capillaries and hematocytes in JKC mouse corneas. Although JKC mouse corneal change is probably secondary to keratitis and is a mouse-specific keratopathy, its pathogenesis may be relevant to that of human keratoconus. Linkage analysis mapped the responsible gene at the markers D13Mit21, D13Mit252, D13Mit279, and D13Mit39, which are located between 21.9 and 34.0 cm of the mouse Chr 13. Candidate genes in this region include genes for cathepsins, interleukin, and chemotaxin. Further study of JKC mice may shed light on pathogenesis of human keratoconus.

Animals↗
PubMed2000

Manifest diabetes and keratoconus: a retrospective case-control study.

PURPOSE: To assess the influence of diabetes on the development of keratoconus to show whether biomechanical effects are also reflected in epidemiology. The two diseases have opposite impact on the biomechanics of the corneal stroma: manifest diabetes stiffens the cornea, whereas keratectasia weakens the tensile strength of the stroma. METHODS: The retrospective case-control study included files of 1,142 patients, with 571 patients in the case group (keratoconus patients) and 571 in the control group (clinical population). The groups were well matched with respect to sex and age. We established the number of diabetics in both groups and compared it statistically by means of the odds ratio to determine whether diabetes can be interpreted as having a "protective effect" whether it is a "risk factor" for the development of keratoconus. RESULTS: Two patients of the keratoconus group had manifest diabetes that developed many years after the diagnosis of keratoconus, while nine cases of diabetes were found in the control group. Statistical analysis revealed a strong protective effect of manifest diabetes regarding keratoconus (odds ratio = 0.2195, P = 0.034). This effect was evident only in type II diabetes patients. CONCLUSIONS: The protective effect of manifest diabetes may be explained by the induction of cross-links in the stroma, preventing biomechanical weakening of the cornea. This study shows that different biomechanical changes can be superimposed and assume epidemiological relevance.

Adult↗
PubMed1990

Alpha-1 proteinase inhibitor levels in keratoconus.

The levels of alpha 1-proteinase inhibitor (alpha 1-antitrypsin) in keratoconus, normal human, and other diseased corneas were examined. Using an immunoperoxidase technique, the presence of this inhibitor was demonstrated in the epithelium, stroma and endothelium of all corneal sections. Compared with normal human controls, the staining intensity in the epithelium and stromal lamellae of keratoconus corneas was markedly reduced. Such a reduction was not seen in either scarred or other diseased corneas. Extracts of keratoconus and normal human corneas were subsequently analyzed for alpha 1-proteinase inhibitor by a dot blot assay using a monoclonal antibody against the inhibitor and a 125I-labelled secondary antibody. In agreement with the immunohistochemical findings, the alpha 1-proteinase inhibitor level found in the epithelium of keratoconus corneas was approximately one-fourth of that found in normal human controls. In addition, the stromal extracts of keratoconus corneas contained about one-sixth the inhibitor level of that in normal human extracts. These results lend further support to the hypothesis that degradation processes may be aberrant in keratoconus.

Adolescent↗
PubMed2005

Unilateral keratoconus in a child with chronic and persistent eye rubbing.

PURPOSE: To report a case of unilateral keratoconus in a 7- year-old female, secondary to chronic persistent eye-rubbing in the absence of any systemic condition. DESIGN: Observational case report. METHODS: In the case of this child, no organic cause was found to explain the onset of keratoconus other than persistent eye-rubbing in the affected eye. RESULTS: Nocturnal eye padding was instigated and the condition stabilized. She was reviewed over a 2-year period of follow-up. CONCLUSIONS: Eye-rubbing has been implicated in the pathogenesis of keratoconus. Eye-rubbing is also often a feature of a number of conditions linked to keratoconus such as Down syndrome, atopic keratoconjunctivitis, mental retardation, and Lebers' congenital amaurosis. There are a number of reports linking eye-rubbing and keratoconus in children, typically in relation to these conditions. However, in this case the keratoconus was secondary to chronic and persistent eye-rubbing in a healthy child.

Child↗
PubMed2004

Videokeratographic anomalies in familial keratoconus.

OBJECTIVE: To analyze videokeratography of relatives of established familial keratoconus (FK) patients to detect low-expressivity keratoconus and improve the diagnosis criteria of forme fruste keratoconus. DESIGN: Multicenter case-control study. PARTICIPANTS: Twenty-three families with 55 clinical keratoconus patients, 89 first-degree relatives, 43 other relatives, and a control group of 130 subjects. METHODS: Videokeratography was performed on both eyes of patients after clinical examination, and corneal maps were analyzed. Statistical comparisons were conducted between first-degree and other relatives and a control population. MAIN OUTCOME MEASURES: Qualitative (using a 0.5-diopter [D] increment scale) and quantitative analyses of videokeratographs. RESULTS: Two corneal patterns were overrepresented in the relatives of FK patients: the J and inverted-J form patterns. Results of the quantitative analysis of these suspect patterns showed that the inferior - superior values (reflecting the inferior - superior dioptric asymmetry) were close to 0.8 D and the Srax (relative skewing of the steepest radial axes) was superior to 21 degrees. CONCLUSION: Our study using topography in clearly established genetic keratoconus families allowed us to detect suspect topographical patterns and brings new data to the difficult task of diagnosing forme fruste keratoconus.

Adolescent↗
PubMed2004

Comparison of deep lamellar keratoplasty and penetrating keratoplasty in patients with keratoconus.

OBJECTIVE: To compare the therapeutic outcomes after deep lamellar keratoplasty (DLK) and penetrating keratoplasty (PK) in patients with keratoconus. DESIGN: Retrospective case-control study. PARTICIPANTS: We reviewed the clinical notes of 47 patients diagnosed clinically with keratoconus who had received DLK (26 eyes of 25 patients) or PK (25 eyes of 22 patients) at Moorfields Eye Hospital or the Royal Shrewsbury Hospital between 1994 and 2001. The patients in the 2 groups were matched for severity of their keratoconus by preoperative visual acuity. METHODS: Deep lamellar keratoplasty was performed with the Melles technique in 7 eyes and the technique described by Sugita and Kondo in 19 eyes. Penetrating keratoplasty was performed with a standard technique using a Hessburg-Barron trephine. A single continuous 16-bite 10-0 nylon suture was placed and adjusted in both groups. MAIN OUTCOME MEASURES: Best-corrected visual acuity (BCVA), refractive results, surgical techniques for DLK, and complication rates were analyzed. RESULTS: The 25 patients with keratoconus who underwent DLK had a mean age of 32.6 years and a median follow-up of 28 months. The mean age of the 22 patients who underwent PK for keratoconus was 34 years. This group was followed up for a median time of 55 months. The median final BCVA of patients in the DLK group was 6/9 and in the PK group 6/6 (no statistical significance). The median result for the final spherical equivalent power in both groups was mild myopia, although the DLK group had more myopia, and the median astigmatism was less than 5.00 diopters cylinder for both groups. Complication rates were similar for DLK and PK, although the nature of the complications varied. CONCLUSIONS: Penetrating keratoplasty is no longer an automatic choice for the surgical treatment for keratoconus; DLK seems to be a safe alternative. Best-corrected visual acuity, refractive results, and complication rates are similar after DLK and PK. Deep lamellar keratoplasty is more technically challenging but allows the risk of endothelial rejection to be avoided and may reduce the risk of late endothelial failure.

Adolescent↗
PubMed2006

Potential complications of ocular surgery in patients with coexistent keratoconus and Fuchs' endothelial dystrophy.

PURPOSE: To describe the potential complications of cataract and refractive surgery in patients with Fuchs' endothelial dystrophy (FED) and keratoconus. DESIGN: Retrospective case series. PARTICIPANTS: Eight patients with FED and keratoconus in a large university group practice. METHODS: We reviewed the clinical and topographic findings of 8 patients (15 eyes) with FED and keratoconus. Clinical examination, corneal topography, specular microscopy were done, and sequential central corneal thickness (CCT) was obtained. Follow-up ranged from 1 month to 6 years. MAIN OUTCOME MEASURES: Findings of keratoconus and FED in preoperative evaluation. RESULTS: Five patients had concomitant cataracts; 3 had refractive errors and sought surgical correction. Cataract surgery was performed on 3 of 5 patients (5 eyes). LASIK was performed on one eye of 3 patients. Of 5 eyes that underwent cataract extraction, 4 had blurry vision after surgery. The interval between the surgical procedure and onset of symptoms ranged from 1 month to 4 years. The causes of decreased vision after cataract surgery were corneal edema and/or corneal ectasia. The CCT readings ranged from 426 to 824 microm. One of 4 symptomatic eyes underwent penetrating keratoplasty. The CCTs of 3 patients (6 eyes) who presented with refractive error ranged from 507 to 565 microm. One eye had undergone an attempted LASIK procedure resulting in a lost cap. Corneal topography and specular microscopy showed the coexistence of keratoconus and FED, and the patients were advised against having LASIK surgery. CONCLUSIONS: Corneal thinning caused by keratoconus and concurrent increase in corneal thickness caused by FED may combine to normalize the corneal pachymetry readings; disease severity may be underestimated, which may lead to unexpected postoperative visual outcomes. Routine use of preoperative topography and specular microscopy may help to avert potential surgical complications.

Aged↗
PubMed2001

Postkeratoplasty keratoconus in a nonkeratoconus patient.

PURPOSE: To determine whether postkeratoplasty keratoconus is caused by a recurrence of the host disease or transferred from the donor. METHODS: Penetrating keratoplasty was performed on the right eye of a 73-year-old woman with pseudophakic bullous keratopathy; her other eye was normal. After keratoplasty, visual acuity decreased secondary to the appearance of irregular astigmatism, central corneal thinning, and stromal striae in the graft. A repeat keratoplasty was performed. Clinical corneal topographic analysis and histopathologic studies were performed. RESULTS: Clinical findings and histopathology of the corneal graft were consistent with keratoconus. The second graft has remained clear for 2 years without signs of keratoconus. CONCLUSION: Classic keratoconus developed in a corneal graft in a patient without preexisting keratoconus. This supports the theory that postkeratoplasty keratoconus may be secondary to transfer of the disease from the donor.

Aged↗
PubMed1988

Comparative studies of collagens in normal and keratoconus corneas.

In this paper we present strong evidence that the aberrations in keratoconus corneas are not directly related to alterations in collagen composition and distribution. This conclusion is based on comparative studies of collagen types I, III, IV, V and the recently described collagen types VI and VII in keratoconus and normal corneas. The data are derived from biochemical analysis of collagen fractions sequentially extracted with pepsin and sodium-dodecylsulphate, from amino acid analysis of hydrolysates of entire corneal tissues as well as from immunoblotting of the extracted collagens with specific antibodies. These antibodies were also used to examine the distribution of the collagens in immunofluorescence experiments on corneal sections. The yields of the collagen extractions were demonstrated to be age dependent but were not altered in keratoconus samples. Apart from one case associated with osteogenesis imperfecta type I, comparative studies of keratoconus and normal corneas showed no differences in collagen composition of the extracts. This was confirmed by amino acid analysis of tissue-hydrolysates. The distributions of collagen types I, III, IV, V, VI and VII in corneal sections were in general unchanged in keratoconus corneas, the only differences being in scar tissues observed in the Bowman layer of some keratoconus samples.

Adult↗
PubMed1988

Keratoconus: I. Biochemical studies.

The present study analyses collagenous and non-collagenous components from age-matched normal and keratoconus corneas. Intact keratoconus corneas showed decreased collagen, total protein, and hydroxylysine levels, with normal reducible collagen cross-linking. Non-collagenous fractions were isolated from corneas with a 4 M guanidine procedure. As demonstrated by PAGE-silver stain, the keratoconus cornea guanidine extracts had a 75 kDa band that was absent in normal cornea guanidine extracts. In addition, there was a markedly increased level of protein, uronic acid and neutral hexose in keratoconus extracts as compared with controls. Our Western blot studies showed increased affinity for the castor-bean agglutinin (RCA120, specific for terminal galactose) in the keratoconus extracts as compared with normals. These data suggest the presence of an abnormal noncollagenous component in keratoconus corneas.

Adult↗
PubMedDate not supplied

Secondary keratoconus with corneal epithelial iron ring similar to Fleischer's ring.

BACKGROUND: Fleischer's ring is considered to be a characteristic of keratoconus, but we have seen a ring similar to Fleischer's ring in patients with secondary keratoconus, in which the cornea becomes thinner secondarily for undetermined reasons. CASES: We report 6 cases of secondary keratoconus with a corneal epithelial ring similar to the Fleischer's ring pattern. OBSERVATIONS: In these 6 cases (2 men and 4 women), the causes of secondary keratoconus were trachoma in 2 cases, trauma in 2 cases, keratitis in 1 case and unknown etiology in one case. All showed thinning of the cornea and a corneal iron ring similar to Fleischer's ring pattern. The corneal button obtained after keratoplasty in 1 case showed the deposition of hemosiderin in the corneal epithelium after staining with Prussian blue. At the same time we confirmed the existence of iron in the corneal epithelium by x-ray ultimate analysis. CONCLUSIONS: All 6 patients we encountered had a past history of corneal disease in their childhood except for 1 case with unknown etiology. Primary keratoconus is also considered to develop by the early teens at the latest. These facts led us to an assumption that the occurrence of some abnormalities in the cornea during the growth period may result in iron deposition in the epithelium and thinning of the stroma. In light of these facts, abnormalities of the iron metabolism must be thoroughly investigated in considering the etiology of keratoconus.

Adult↗
PubMedDate not supplied

The expression of laminin-5 and ultrastructure of the interface between basal cells and underlying stroma in the keratoconus cornea.

PURPOSE: We investigated the expression of laminin-5 and integrins, and the ultrastructure of the interface between basal cells and the basement membrane in the keratoconus cornea. These findings were compared to those in normal central cornea and limbus. METHODS: Frozen sections of the normal cornea (center and limbus) and the keratoconus cornea were immunostained with monoclonal antibodies against three chains of laminin-5 and integrins. To investigate the ultrastructure of the interface between basal cells and the underlying stroma, we used transmission electron microscopy. RESULTS: As compared to those in the normal central cornea, immunostaining patterns of the three chains of laminin-5 were thick and irregular in the keratoconus cornea and the normal limbus. Using electron microscopy analysis, the same characteristic structure of the interface between basal cells and the underlying stroma was recognized in the keratoconus cornea and the normal limbus. The expression of integrin alpha(6)beta(4) was restricted to the basal aspect of basal cells in the normal cornea. In the keratoconus cornea, however, integrin alpha(6)beta(4) was expressed in all aspects in basal and suprabasal cells. CONCLUSION The expression patterns of laminin-5 and the ultrastructure of the interface between basal cells and the basement membrane in the keratoconus cornea were similar to those in the normal limbus.

Adult↗
PubMedDate not supplied

Keratoconus.

Keratoconus is a bilateral noninflammatory corneal ectasia with an incidence of approximately 1 per 2,000 in the general population. It has well-described clinical signs, but early forms of the disease may go undetected unless the anterior corneal topography is studied. Early disease is now best detected with videokeratography. Classic histopathologic features include stromal thinning, iron deposition in the epithelial basement membrane, and breaks in Bowman's layer. Keratoconus is most commonly an isolated disorder, although several reports describe an association with Down syndrome, Leber's congenital amaurosis, and mitral valve prolapse. The differential diagnosis of keratoconus includes keratoglobus, pellucid marginal degeneration and Terrien's marginal degeneration. Contact lenses are the most common treatment modality. When contact lenses fail, corneal transplant is the best and most successful surgical option. Despite intensive clinical and laboratory investigation, the etiology of keratoconus remains unclear. Clinical studies provide strong indications of a major role for genes in its etiology. Videokeratography is playing an increasing role in defining the genetics of keratoconus, since early forms of the disease can be more accurately detected and potentially quantified in a reproducible manner. Laboratory studies suggest a role for degradative enzymes and proteinase inhibitors and a possible role for the interleukin-1 system in its pathogenesis, but these roles need to be more clearly defined. Genes suggested by these studies, as well as collagen genes and their regulatory products, could potentially be used as candidate genes to study patients with familial keratoconus. Such studies may provide the clues needed to enable us to better understand the underlying mechanisms that cause the corneal thinning in this disorder.

Cornea↗
PubMed2002

Role of Orbscan II in screening keratoconus suspects before refractive corneal surgery.

OBJECTIVE: To evaluate the relationship between videokeratographic keratoconus screening programs and Orbscan II topography. DESIGN: Prospective, observational case series and instrument validation study. PARTICIPANTS: Sixty consecutive eyes with suspicious videokeratography (TMS-1, Tomey Technology, Waltham, MA) were evaluated before undergoing laser in situ keratomileusis (LASIK) surgery. A control group of 50 consecutive eyes without suspicious features by videokeratography was also evaluated. METHODS: Keratoconus screening programs, using the Rabinowitz and Klyce/Maeda methods and Orbscan II (Bausch & Lomb, Claremont, CA) topographies were performed on these patients. MAIN OUTCOME MEASURES: Specific parameters evaluated on the Orbscan II topographies were anterior elevation, posterior elevation, and thinnest pachymetry. RESULTS: Compared with a control group of patients without suspicious videokeratography, there was a statistically significant difference in the mean posterior elevation and mean anterior elevation in the groups with positive keratoconus testing with the Rabinowitz or Klyce/Maeda methods. For patients who met both the Rabinowitz and Klyce/Maeda criteria for keratoconus, the mean posterior elevation was 44 +/- 2.5 micro m compared with a posterior elevation of 21 +/- 0.6 micro m for the control group. There was no statistically significant difference in the mean thinnest pachymetry between the control group and all keratoconus suspect groups. CONCLUSIONS: Patients with positive keratoconus screening tests have higher anterior and posterior elevation on Orbscan II topography. When used in combination with videokeratography, the Orbscan II topography system may be helpful in identifying patients who are potentially at high risk for developing ectasia after LASIK.

Adult↗
PubMed1989

Effect of recipient-donor trephine size disparity on refractive error in keratoconus.

A retrospective study was performed to evaluate the effect of recipient-donor trephine disparity on refractive error and corneal curvature post-suture removal in keratoconus. A double running suture technique was used and donor corneas were trephined from the endothelial side. When keratoconus patients with 0.25-mm larger donor than recipient trephines were compared with keratoconus patients with the same size recipient and donor trephines, a statistically significant increase in the mean keratometer value (45.4 and 43.8 diopters [D], respectively; P = 0.03) and increase in myopic spherical equivalent (-3.5 and -1.8 D, respectively; P = 0.03) was found. When keratoconus patients were compared with phakic Fuchs' dystrophy patients (both groups had 0.25-mm oversize donor trephines), the keratoconus group had a statistically significantly higher myopic spherical equivalent (-3.5 and -1.4 D, respectively; P = 0.03) despite only a 0.7-D difference in mean keratometer value which was not statistically significant (45.4 and 44.7 D, respectively). This study supports the hypothesis that the degree of post-penetrating keratoplasty myopia in patients with keratoconus can be decreased by reducing recipient-donor trephine disparity.

Corneal Dystrophies, Hereditary↗