A high body mass index strengthens the association between the time of eye rubbing and keratoconus in a Chinese population: a case control study.

BACKGROUND: Although body mass index (BMI) and eye rubbing are linked to an increased risk of keratoconus (KC), the interactive effect of eye rubbing and BMI on KC is largely unknown. This study aimed to evaluate the independent and interactive effects of BMI and eye rubbing on KC and to further explore the role of environmental factors on the occurrence of KC. METHODS: A total of 621 individuals (291 KC patients and 330 control individuals) were enrolled in this hospital­based study on KC patients in Central China after individuals missing BMI data were excluded. BMI was calculated as weight in kilograms divided by the square of height in meters. Data on eye rubbing was recorded through face-to-face interviews. Generalized linear regression models were used to analyze associations among BMI, eye rubbing and KC. Interaction plots were used to describe the interactive effects of BMI and eye rubbing on KC. RESULTS: The ß and 95% confidence interval (CI) were 0.923 (0.112, 1.733) (p = 0.026) and 3.356 (1.953, 4.759) (p < 0.001), respectively, for the effect of each 10 kg/m2 increase in BMI and each 1 min increase in eye rubbing on KC. The interaction of BMI and eye rubbing were positively correlated with KC (p < 0.001). CONCLUSION: These findings suggested that a high BMI aggravated the negative effect of eye rubbing on KC, implying that individuals with a high BMI may be more susceptible to exposure to eye rubbing, which is related to an increased risk of KC.

Eye Rubbing in Chinese Patients With Keratoconus: A Multicenter Analysis.

PURPOSE: To investigate the eye rubbing habits of Chinese patients with keratoconus. METHODS: This study was carried out from 2018 to June 2022 at Shandong Eye Hospital, Qingdao Eye Hospital, and Henan Eye Hospital. The study compared the number of patients who rubbed their eyes between medical records and second time questionnaires, eye rubbing of patients with myopia and patients with keratoconus, and disease severity between patients with keratoconus. A questionnaire survey of ophthalmologists was conducted to determine their degree of awareness that eye rubbing is a risk factor for keratoconus. RESULTS: The study assessed 799 patients with keratoconus and 798 control patients, and 97 ophthalmologists. The average proportion of patients with keratoconus who rubbed their eyes was 31.0% in the medical records with an increasing trend related to the increase in ophthalmologists' awareness, 66.6% after the second follow-up, and 25.4% among patients with myopia. After multivariate analysis, the following variables showed significant results: eye rubbing frequency more than 10 times/day (odds ratio [OR], 9.168; P < .001); rubbing with knuckles (OR, 9.804; P = .001); and prone sleep position (OR, 12.427; P < .001). The proportion of patients who rubbed their eyes with stage IV keratoconus was 71.9%, 18.9% higher than those with stage I, 4.8% higher than stage II, and 17.8% higher than stage III. CONCLUSIONS: The proportion of Chinese patients with keratoconus who rubbed their eyes was relatively high. The main reasons for the low proportions reported were lack of attention. Clinical attention should be paid to eye rubbing in patients with keratoconus who should be educated to avoid it. [J Refract Surg. 2023;39(10):712-718.].

Eye Rubbing and Transient Corneal Ectasia Detected by Topography in a Pediatric Patient.

ABSTRACT: We report on a 13-year-old girl undergoing changes in the refraction of her OS associated with eye rubbing. Corneal topography showed a corneal deformation in OS, classified as stage 1 keratoconus according to the Krumeich classification. A significant reduction in eye rubbing led to a normal corneal shape at the 1-year follow-up. Transient and fully reversible corneal ectasia can be caused by eye rubbing in pediatric age. This may have implications when counseling very young patients with eye rubbing.

The Youngest Patient with Bilateral Keratoconus Secondary to Chronic Persistent Eye Rubbing.

We present the case of a four-year-old girl with bilateral keratoconus secondary to chronic persistent eye rubbing. She was referred to our clinic with intractable ocular itching and low vision. According to her family, she was generally rubbing her eyes. On slit-lamp biomicroscopic examination, bilateral papillary reactions were seen on the upper tarsal conjunctiva. Clinical examination and corneal topography were compatible with keratoconus. The patient's visual acuity was not evaluated because of cooperation difficulties. Systemic examination was normal. In fact, trauma may be the common underlying factor in eye rubbing and may cause development of keratoconus, even in the early years. To the best of our knowledge, this is the youngest patient with bilateral keratoconus secondary to chronic persistent eye rubbing in the literature. Keratoconus should be kept in mind in patients with severe ocular itching, even in small children.

Inflammation and keratoconus.

Keratoconus (KC) has been traditionally classified as a noninflammatory disease. Barring loss of function, the other classic signs of inflammation (heat, redness, swelling, pain) are not usually obvious or even apparent in KC. This clinical perspective examines the evidence and implications of numerous inflammatory processes that have been recognized in the tears of KC patients as well as some inflammation relevant differences found in the KC cornea. The roles of inflammation in corneal trauma attributed to eye rubbing and/or contact lens wear are examined as is the significance of atopy, allergic disease, dry eye disease, degradative enzyme activity, wound healing, reduced anti-inflammatory capacity, and ultraviolet irradiation. It is possible that any comorbidity that is inflammatory in nature may add synergistically to other forms of KC-related inflammation and exacerbate its pathogenetic processes. For example, some features of inflammation in ocular rosacea and associated corneal thinning and distortion could have some possible relevance to KC. An analogy is drawn with osteoarthritis, which also involves significant inflammatory processes but, like KC, does not meet all the classic criteria for an inflammatory disease. Classifying KC as quasi-inflammatory (inflammatory-related) rather than a noninflammatory disease appears to be more appropriate and may help focus attention on the possibility of developing effective anti-inflammatory therapies for its management.

What causes keratoconus?

PURPOSE: The etiology of keratoconus has been the subject of numerous studies. Here, we review the body of literature that attempts to determine what causes keratoconus. METHODS: A review of the published literature was performed to evaluate the possible causes of keratoconus and how the different etiologies may play a role in the development of this disease. RESULTS: Peer-reviewed published papers and recent abstracts concerning the different etiologies of keratoconus were reviewed and discussed. Biochemical, genetic, and environmental factors are reviewed. The role of eye rubbing and atopic disease are explored. CONCLUSIONS: We agree with the hypothesis that there is a genetic predisposition that requires a "second hit" or environmental event to elicit progressive disease in keratoconus. Eye rubbing may serve as the "second hit" in some predisposed individuals. Inflammatory mediator studies question if keratoconus is really a noninflammatory thinning disorder of the cornea.

Keratoconus caused by eye rubbing in patients with Tourette Syndrome.

OBJECTIVE: To report the association between keratoconus and Tourette Syndrome (TS) and to reinforce that eye rubbing may be a causative factor for keratoconus. DESIGN: Observational case series. PARTICIPANTS: Three patients with TS who presented with clinical and topographic findings suggestive of asymmetric or unilateral keratoconus. METHODS: Evaluation of patients in a single clinical practice. RESULTS: Patients' histories revealed asymmetric or unilateral rubbing of the affected eye as a result of a TS tic. Other organic causes associated with keratoconus were absent in these patients. CONCLUSIONS: A possible association between TS and keratoconus exists with chronic eye rubbing being the suggested mechanism. Eye rubbing seems to be an important causative factor for keratoconus.

Mechanisms of rubbing-related corneal trauma in keratoconus.

PURPOSE: Corneal scarring in keratoconus, which is observed prior to contact lens wear and in association with a chronic habit of abnormal rubbing, suggests a keratocyte change to a repair phenotype in response to rubbing trauma. METHODS: This review examines known and putative mechanisms for rubbing-related corneal trauma and cone formation. RESULTS: Responses to eye rubbing (and possible causal links) may include increased corneal temperature, epithelial thinning, increased concentrations of inflammatory mediators in the precorneal tears, abnormal enzyme activity, large intraocular pressure spikes, high hydrostatic tissue pressure, thixotropically reduced ground substance viscosity, temporary displacement of ground substance from the corneal apex, buckling and flexure of fibrils associated with waves of corneal indentation, biomechanically coupled curvature transfer to the cone apex, slippage between collagen fibrils at the cone apex, and changes to keratocytes due to mechanical trauma and/or high hydrostatic pressure, in addition to scar formation. Cone formation appears to depend on a loss of shear strength and may be a consequence of a reduction in ground substance viscosity and glue function, which could allow the cornea to bend and yield to intraocular pressure. CONCLUSIONS: For some forms of keratoconus, a reduction in shear strength and cone-forming deformation may be responses to rubbing trauma. Some of the mechanisms for corneal rubbing trauma may be relevant to post-laser-assisted in situ keratomileusis ectasia or complications following other types of corneal surgery. There appear to be indications for the control of chronic habits of abnormal rubbing.

Eye rubbing as an apparent cause of recurrent keratoconus.

PURPOSE: To report a case of recurrent keratoconus after penetrating keratoplasty (PKP) because of allergic conjunctivitis. METHOD: Case report. RESULTS: A 23-year-old woman who had successful bilateral PKP presented with complaints of visual impairment 3 years after the last examination. She also complained of severe ocular itching and hyperemia, and she reported a history of vigorous eye rubbing. The diagnosis of recurrent keratoconus was confirmed based on clinical findings and topographic features. CONCLUSIONS: A recurrence of keratoconus can occur because of itch-provoked rubbing of the eyes. Patients who had PKP should be evaluated for a history of ocular allergies.

Bilateral recurrent self-induced keratoconus.

The observational case describes bilateral recurrent keratoconus in corneal transplants performed in a patient with self-induced keratoconus secondary to compulsive eye rubbing. Slitlamp findings demonstrated corneal stromal thinning and scarring in the patient's right eye and temporal corneal hydrops in his left eye. Videokeratography of the right eye confirmed the presence of corneal steepening and irregular astigmatism, consistent with the diagnosis of keratoconus involving each transplant. Together with the history of ongoing compulsive eye rubbing, these findings support the concept that chronic mechanical trauma to the cornea may contribute to the development of keratoconus.

Management of chronic habits of abnormal eye rubbing.

A review of the provocations and the consequences of chronic habits of abnormal rubbing indicates a range of possible adverse responses. Gentle rubbing may double intraocular pressure. However, the combination of tight eye closure and forceful rubbing may raise intraocular pressure to more than 10 times normal levels. The possibility that, in susceptible individuals, chronic habits of abnormal rubbing may lead to the development or progression of keratoconus has been extended to the possibility of rubbing related adverse responses in other diseases and conditions. The adverse consequences of rubbing appear to be active processes, in contrast to the apparent passive nature of any recovery from those responses. Avoidance of the possibility of permanent adverse changes is clearly preferable. However, advice to avoid rubbing may not be successfully followed. Education and counseling appear to be the foundations for helping patients to control chronic habits of abnormal rubbing. An instrument has been developed as the basis for patient education and counseling for this purpose. It is intended as a take-home document which might have relevance to other family members. The widening of the application of this form of patient education to all members of a family, and a wider range of conditions, may produce beneficial synergy with advantage to patients who may have the most to gain from controlling chronic habits of abnormal rubbing.

Abnormal rubbing and keratectasia.

PURPOSE: Hypotheses for the varied pathogenesis of the different forms of keratoconus have been outlined. Against this background, the possibility that abnormal rubbing causes or contributes to the development or progression of some forms of keratoconus has been examined. METHODS: Circumstantial evidence that shows an association between abnormal rubbing and keratoconus is reviewed, and a wide range of different forms of abnormal rubbing is described. Also examined is evidence of several processes whereby the cornea appears to be, or could be, adversely affected by mechanical trauma caused by rubbing. Conditions that may increase susceptibility to mechanical rubbing trauma have been discussed. RESULTS: Evidence of a role for inflammatory mediators in the pathogenesis of keratoconus appears to void the description of keratoconus as a noninflammatory condition. When vigorous knuckle-rubbing forces are located on the normal peripheral cornea, the thinner or weakened cone apex may be exposed to high intraocular pressure distending forces that may tend to promote ectasia. CONCLUSIONS: It appears reasonable to conclude that abnormal rubbing is a cause of some types of keratoconus, not because all abnormal rubbing, or only abnormal rubbing, leads to the development of some types of keratoconus, but because abnormal rubbing may increase the likelihood of the development of some forms of keratoconus. Abnormal rubbing habits may commence or continue after routine contact lens wear is established. Any associated rubbing or contact lens trauma may contribute to the progression of keratoconus. The abnormal rubbing-ectasia association in keratoconus may extend to other forms of keratectasia, including that seen after laser in situ keratomileusis, for which a contributory abnormal rubbing hypothesis may be appropriate.

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.

Asymmetric keratoconus attributed to eye rubbing.

PURPOSE: To report a series of cases with asymmetric keratoconus attributed to eye rubbing, discuss its pathogenesis, and review the literature. METHODS: Case reports and literature review. RESULTS: A careful history obtained from 5 patients with asymmetric keratoconus revealed habitual eye rubbing of the more severely affected eye. CONCLUSIONS: Trauma, such as occurs with habitual eye rubbing, plays a role in the pathogenesis of keratoconus.

On the location of the cone and the etiology of keratoconus.

I suggest that the location of the cone in keratoconus is most often located in the paracentral inferonasal quadrant of the cornea due to the presence of the most senile epithelial cells in this location. These cells may be more vulnerable than younger epithelial cells to the chronic subtle trauma of eyelid rubbing and may be more prone to release enzymes that thin the cornea.