The Relationship Between Keratoconus And Eye Rubbing: A Review

Abstract
Keratoconus is a non-inflammatory condition which develops gradually; It is characterized by corneal thinning and ectatic protrusion. Keratoconus prevalence varies in different areas depending upon numerous factors affecting its occurrence. There are risk factors for developing keratoconus such as demographic and environmental factors which have been explained in greater detail in the review below. It was suggested that eye rubbing was associated with the development of keratoconus and the same has also been examined in the review below. The primary goal of this review was to summarize the medical literature about keratoconus and to determine the role of eye-rubbing in the aetiology of the disease. A variety of 24 short articles was evaluated. There are several search phrases used such as keratoconus, aetiology of keratoconus, eye rubbing, keratoconus prevalence, keratoconus and eye rubbing relationship. We concluded that eye rubbing triggers the thinning of keratocyte, as well as the degree of effect of eye scrubbing relies on the period as well as force of executing eye rubbing. It is recommended to avoid eye rubbing to avoid keratoconus, this can be accomplished by preventing itching in the eyes due to various causes and treating dryness of the eyes by medication and also preventing putting on eye contact lenses for prolonged periods of time.

The Connection Between Keratoconus And Eye Rubbing: An Evaluation

Introduction
Eye conditions are considered an important health issue in the Middle East, particularly in Saudi Arabia. Keratoconus is an eye condition that causes curvature of the cornea gradually, changing it from a balanced dome form into an asymmetric cone shape. This results in lowered visual acuity as well as a change in eyeglasses prescription. It was defined first in 1854, this condition is characterised by obscured vision secondary to irregular astigmatism.
It affects all ethnic groups. However, it is much more common in Caucasians as well as Asians. The prevalence of keratoconus varies among researches as a result of the distinctions in diagnostic examinations in addition to the interpretation of keratoconus; the occurrence was reported to be 1 instance in every 2000 individuals globally. In Saudi Arabia, it was found that keratoconus in the previous 20 years was the primary factor for corneal transplantation. A number of factors enhance the growth of keratoconus consisting of demographic factors and environmental factors, the demographic variables consisting of ethnic distinctions as well as genetic variables, while environmental factors include eye rubbing, atopy and also ultraviolet (UV) exposure. Supposition of keratoconus progression by eye rubbing is talked about in numerous released case studies such as those that suggest the association between keratoconus and also eye rubbing. Eye rubbing is a normal activity of many individuals that happens in response to psychological anxiety, tiredness or eye irritability, it also occurs prior to rest and when waking. Eye rubbing can be evoked by symptoms of allergy and dryness of the eye. The existing evaluation intends to figure out the association between keratoconus and eye rubbing by assessing the previous researches as well as to summarize the literary works and data regarding keratoconus.
In this review, we have actually made use of the internet as a source to examine write-ups discussing the current topic. The sources are reviewed to have access to the chosen short articles. There are numerous key phrases used such as keratoconus, aetiology of keratoconus, eye rubbing, keratoconus prevalence, keratoconus and eye rubbing relationship; and we acquired 24 short articles, we excluded 13 write-ups as they did not satisfy the research study requirements. Eleven short articles only are included as they meet the study standards; 3 of them were evaluation posts, and 8 were originals articles. The short articles included in this review were published in the English language between 2003 and 2017. The information drawn out from the selected short articles consisted of a definition of keratoconus, its pathology, occurrence, categories, symptoms, medical diagnosis, risk factors, and management.

KERATOCONUS
Keratoconus Definition
Keratoconus is a term derived from the Greek word keras (horn) as well as konos (cone) which suggests cone-like outcropping of the cornea. Keratoconus is an eye condition that causes curvature of the cornea gradually, transforming it from a balanced or symmetrical dome shape into an asymmetric cone form resulting in various changes, the primary one being the change in eyeglasses prescription over time. This leads to lowered visual acuity and changes in eyeglasses’ prescription. This disorder has actually been recognized in the middle of the 19th century. Keratoconus is a non-inflammatory condition that results in thinning of the cornea, it normally occurs bilaterally], in 96% of cases, yet it can develop asymmetrically. The substantial bulk of cases have bilateral keratoconus; however, they are asymmetric in extent as well as development.

Keratoconus Pathology
The illness may start as unilateral, but finally, the other eye comes to be involved. All cornea layers are impacted by keratoconus, yet corneal stroma is one of the most significant. Thinning of corneal stroma occurs at the inferior or central portion of the cornea, and also it comes to be thinner and also causes distortion of the cornea leading to a cone form of the cornea, this consequently results in changes in refractive powers.
The thinning of the superior part of the cornea is extremely rare. Keratoconus is an acquired ectasia which triggers irregular, progressive, myopic astigmatism. Myopia as well as irregular astigmatism are induced by the thinning of the cornea which causes light or even marked visual impairment. Corneal oedema and decompensation cause corneal scarring which additionally lowers the visual acuity in the advanced cases.
Keratoconus shows up between 10 and 20 years of age. At puberty, keratoconus has its most common start, as well as it develops in most cases till the third or 4th decade of life, after that it normally stops.

Keratoconus Prevalence
Keratoconus prevalence differs between different researches; the prevalence varies from 1/500 to 1/2000 cases worldwide. Corneal topography tools were utilized in current studies and prevalence was found to be greater.
It was reported that in the general population the prevalence rates ranged from 8.8 to 229 cases/105 annually. The occurrence in Russia was estimated to be 0.3/ 105 while occurrence in the US and also central India was reported to be 1 per 2000 and 2300/105 specifically.
In Tehran, in research from Iran, the keratoconus prevalence was 3.3%. An evaluation from Saudi Arabia pointed out the occurrence in a number of nations; it was stated that the occurrence in Columbia was 3900/105, in Yemen was 15 500/105 and 9400/105, Keratoconus prevalence in the Republic of Macedonia was estimated to be 6.8 cases/105, and in Israel was 2340/105, a study from Saudi Arabia, revealed that the occurrence of keratoconus represented 0.81/ 105 citizens. Nevertheless, the authors recommended that these outcomes may not represent the prevalence in Saudi Arabia presuming that patients might be referred to other ocular facilities or health centers.
The prevalence of keratoconus in a Province in Saudi Arabia by utilizing a clinic-based protocol was found as 20 cases/105, another study from another city in Saudi Arabia, revealed that the prevalence in the general population was 4/105, which was less than the prevalence reported from the province. The variance in prevalence rates between different regions in the world go back to differences in various factors between various researches such as methods of analysis as well as analysis standards.

Classification of Keratoconus
Keratoconus is classified right into three broad groups. The first involves keratoconus associated with unusual genetic disorders (such as neurofibromatosis, Down disorder as well as nail-patella syndrome). The second includes keratoconus connected with some factors such as eye rubbing, atopy, contact lens wear, Leber hereditary amaurosis, mitral shutoff prolapses and positive family background, the 3rd and also last category entails keratoconus with no association as well as of unknown aetiology.

Symptoms of Keratoconus
Symptoms of keratoconus differ according to the intensity of the condition. In the early stages of the illness, the people might experience no symptoms, nonetheless they may experience some symptoms which include enhanced sensitivity to light, seeing lights or haloes around objects, eye strain, irritability, allergy, discomfort, need for rubbing, reduced resolution in all distances and also obscured vision. The symptoms vary from moderate to severe visual issues, as an outcome of near-sightedness, irregular astigmatism, and frequently, corneal scarring.
There are three symptoms of keratoconus viz. thinning of the stromal cornea with subsequent ectasia, Fleischer’s ring which reflects the deposition of iron (hemosiderin pigment) in the basal layer of the corneal epithelium and also the breaks in Descemet’s and also Bowman’s layers and all these symptoms allow us to make an accurate diagnosis of the presence of keratoconus in the eyes of the patient.
Vogt’s striae and Fleischer’s ring are vertical lines produced by compression of Descemet’s membrane which might be observed near the apex of the cone. The ectatic cornea becomes noticeable at the advanced phase of keratoconus; the protrusion presses the lower lid out in a V-shaped dent by looking downward, this is called Munson’s sign. In the most extreme and advanced cases, breaks in Descemet’s membrane layer occur, referred to as hydrops, have actually been observed. Stromal oedema as well as vision loss with linked pain arise from these breaks.

Medical diagnosis of Keratoconus
Medical diagnosis of keratoconus relating to symptoms in early and mild stages is tough as the first symptoms of keratoconus are similar to that of various other ocular problems. The classic means to assess keratoconus entail exterior assessment of the eye using both anterior segment expert opinion and utilization of the same, extensively used scales. Keratoconus diagnosis ended up being simpler as a result of breakthroughs in corneal imaging. Electronic and molecular approaches consisting of elevation-based slit scanning and topographic are offered currently and increased drastically as an important tool for differential diagnosis and also categorization of keratoconus.
Retinoscopy can reveal irregular astigmatism as the condition progresses. However, corneal topography is one of the most delicate strategies to identify early keratoconus. Corneal topography and also tomography analysis tools can be successfully made use of to identify keratoconus and to establish its level of severity; these techniques allowed accomplishing fine screening of the central corneal steeping, asymmetry of the interior corneal steeping and also asymmetry of optical power. Ultrasonic pachymetry can show the difference between the superior and inferior thickening of the cornea, hence keratoconus grading can be done.
The corneal topography has actually become a routine ophthalmic technique, it is considered now as the basic gold standard examination in both tracking and diagnosing of keratoconus. The shape of the cornea on the topographic differs between keratoconus and normal cornea qualitatively as well as quantitatively, the cornea looks like an asymmetric bow-tie with a skewed radial axis in case of keratoconus when identifying it qualitatively. In the quantitative evaluation of keratoconus, the location of corneal power increased, and inferior-superior (IS) power shows up asymmetrical. There were numerous video-keratography obtained indices which have actually been developed to assess the topographic pattern of keratoconus quantitatively. Posterior corneal surface elevation has an important function as a non-invasive method of medical diagnosis. It assists in measuring the degree of the injury, and along with it represents a very fine approach of medical diagnosis.

Causes as well as Factors of Keratoconus Risk
The risk factors of keratoconus consist of demographic variables, ethnic differences, genetic aspects as well as environmental factors. The environmental factors entail eye rubbing, atopy and UV exposure.
Environmental as well as hereditary variables are thought about one of the possible reasons, some congenital diseases that cause keratoconus, but there may still be numerous defects to be found. In many cases, cone-like cornea shows up in a variety of family members, especially in family members where kinship takes place. Where scientists had the ability to recognize a chromosome link has a role in this case. Keratoconus might be connected with various other allergic illnesses such as hay fever, eczema, bronchial asthma, this condition may be clearly related to the issue of eye rubbing, which may trigger a rapid worsening. It may also affect people who usze contact lenses.
In the existing evaluation, we will certainly focus on eye rubbing as a risk factor for keratoconus in the following paragraphs.

EYE RUBBING
Meaning as well as Reasons for Eye Rubbing
Eye rubbing is a common behaviour that happens spontaneously before sleep, when awakening and also throughout the day as a response to eye inflammation, tiredness and emotional tension. It was stated that uncommon eye rubbing might be secondary to aggravating symptoms such as dry skin and itching, and it can be psychogenic with compulsive or unwarranted rubbing. Atopy as well as allergy were one of the most dominant risk factors for the persistent practice of unnatural eye rubbing] Also, compulsive behaviour, psychological stress and anxiety or emotional tension and also psychogenesis are associated with unusual eye rubbing.

Eye rubbing as a Risk Factor for Keratoconus
Persistent, irregular eye rubbing is related to keratoconus development. Recurring gentle and energetic knuckle-grinding rubbing are connected with progression of keratoconus. There are lots of factors for this eye rubbing habit. Nevertheless, the reason will certainly not impact the habit of persistent eye rubbing in the advancement of keratoconous. Bilateral keratoconus was reported in a child, 4 years of age who practised persistent eye rubbing for long.
In a study that consisted of 240 keratoconus patients, it was found that 65.6% of them had a history of eye rubbing, which is definitely a statistically significant number. It was also discovered that 48% of keratoconus patients rubbed their eyes. In the Saudi research study, it was found that 44.8% of individuals had the eye rubbing habit. In another case-control study, it was reported that in 218 keratoconus patients and 183 healthy age-matched controls, eye rubbing existed in 83% of keratoconus subjects compared to 58% in healthy controls which is a substantial difference and helps solidify our research and establish the role of eye rubbing. A research from Iran revealed that there was a healthy relationship between the positive history of eye rubbing as well as occurrence of keratoconus.
In a Saudi research, it was reported that one of the most common risk factors between keratoconus patients were eye-rubbing, accounting for 100%. Positive history of eye rubbing stood for a higher prevalence of keratoconus patients. Corneal curvature worsens by the asymmetric eye rubbing. Irregular keratoconus was discovered to be connected to the eye that was badly affected by abnormal eye rubbing. Monocular keratoconus in a person with bilateral eye-rubbing was found to be associated with hand dominance. Keratoconus develops after 14 months in cases of persistent compulsive eye rubbing as well as psychogenic eye rubbing. Also, it was discovered that eye rubbing was a substantial risk in the development of keratoconus in patients with a background of parental consanguinity.
Eye rubbing stood for 91.8% of 49 children patients, where eye rubbing was secondary to generated ametropia or atopy. Various other research studies fell short to discover an association between eye rubbing and keratoconus, as a study from Lebanon reported no association between eye rubbing as well as keratoconus, where it showed that 12% of keratoconus patients had a family history of keratoconus, while eye rubbing was not a considerable factor, so there are varying research studies and varying results of these research studies. In the two other studies, it was found that no substantial association between keratoconus and eye rubbing.

Mechanism of Keratoconus due to Eye rubbing
A number of mechanisms have been recommended for keratoconus progression, secondary to eye rubbing. The cornea is flexible and, as a result, vulnerable to changes in shape. The regularity and force of rubbing are the factors that affect corneal eye rubbing related modifications; these changes happen as the cornea is flexible, that made it susceptible to changes in shape. It was found that the keratocyte density in human corneas was reduced significantly by slight eye rubbing for 10 seconds repeated 30 times over 30 minutes. Additionally, changes in intraocular pressure (IOP) due to eye rubbing can cause the progression of keratoconus, where indirect traumatization to keratocytes results from the significant variations in IOP, this traumatization to keratocytes consequently causes keratoconus. Numerous studies reported that the level of IOP was found to increase by increasing the compressive rubbing forces that applied in eye rubbing at the corneal surface.

Eye Complications Resulting from Eye Rubbing
Intense hydrops can be caused in patients with keratoconus of 9 years of age as a result of continuous eye rubbing. Hydrops in keratoconus patients might result from the mechanical stress of rubbing. Numerous research studies revealed an association between the development of severe hydrops and strenuous eye rubbing. Results of eye rubbing on corneal topography were observed, where eye rubbing raises the irregularity index of the corneal surface, after 60 seconds of eye rubbing, a 0.5 diopter of astigmatism was found to be generated, which is highly statistically significant caused by the irregularity of the corneal surface.

Management of Keratoconus
The management of keratoconus varies according to the extent of the instance, so there was no single method being the best for all patients. Eyeglasses can be utilized to correct moderate keratoconus. Rigid contact lenses can be called for when the patient becomes incapable to acquire excellent visual acuity as a result of greater order aberrations and enhancing levels of irregular astigmatism, the rigid contact lenses in this case properly offer a new anterior surface to the eye. There are a number of types of lens designs for keratoconus and also it is hard to predict which one is appropriates for the patient, in addition, the corneal collagen cross-linking affects the regularity of keratoplasties in patients with keratoconus.
Keratoplasty can be used as a separate administration procedure for keratoconus, as it has various advantages upon long and short term such as preserving the health of the host endothelium as well as stopping the rejection of the endothelial graft. On top of that, as the graft survival is an essential concern, it assists in the promotion of graft survival.

CONCLUDING THOUGHTS
Keratoconus is an eye disorder; its prevalence evaluation differs according to a number of factors. Several factors are impacting the growth of keratoconus; eye-rubbing is the primary factor which is creating a significant number of eye injuries especially keratoconus. Eye rubbing triggers the thinning of keratocyte, as well as the level of outcome of eye rubbing depends upon the period as well as force of executing eye rubbing. Although few studies did not find a substantial association between keratoconus and eye rubbing, the substantial bulk of the research studies validated the correlation. It is recommended to avoid eye rubbing to prevent keratoconus; this can be attained by the treatment or prevention of allergy causes and also treatment of dryness of the eye. On top of that, it is suggested to avoid wearing contact lenses if they were unneeded, additionally it is important to increase awareness of people about the risk of eye rubbing as most of the people are doing it as a habit.

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