Vision therapy and computer orthoptics: evidence-based approach to use in your practice

Convergence insufficiency is a commonly seen disorder of the vergence system. Its clinical characteristics and symptoms have been well described by Duane and von Graefe. Laboratory studies have clarified the vergence pathway, which includes a bi-phasic response. Several recent randomized controlled trials show the effectiveness of common treatment modalities, including pencil pushups, computer orthoptics, and office-based therapy. More studies are needed to investigate the possibility that other treatments may treat convergence insufficiency in a more profound way by acting on other parts of the vergence system.

[Screening for visual impairment in children: new tests and the place of the orthoptist]

The fragility and plasticity of visual function in children necessitates early detection and treatment of visual disorders. New approaches such as portable automatic refraction, tonometry and digital fundus examination have improved the quality of screening The problem now is a lack of ophthalmologists. One possible solution is to redefine the role of orthoptists. The waiting time for an ophthalmologist appointment is very long in some parts of France (up to a year), because of a training quota established in the 1980s, as well as retirements (average age 52 years), and a concentration of specialists in the south of France and around medical schools. Today, France trains only 80 specialists per year, whereas twice as many are needed Anglo-Saxon countries (US, Canada, United Kingdom) have created a profession--the optometrist--that is intermediate between the optician and the ophthalmologist. This profession is not recognized in France, yet optometrists are capable of detecting many anomalies and quickly referring a child to a specialist.

Non-surgical interventions for convergence insufficiency

BACKGROUND

Convergence insufficiency is a common eye muscle co-ordination problem in which the eyes have a strong tendency to drift outward (exophoria) when reading or doing close work. Symptoms may include eye strain, headaches, double vision, print moving on the page, frequent loss of place when reading, inability to concentrate, and short attention span.

OBJECTIVES

To systematically assess and synthesize evidence from randomized controlled trials (RCTs) on the effectiveness of non-surgical interventions for convergence insufficiency.

SEARCH STRATEGY

We searched The Cochrane Library, MEDLINE, EMBASE, Science Citation Index, the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (www.clinicaltrials.gov ) on 7 October 2010. We manually searched reference lists and optometric journals.

SELECTION CRITERIA

We included RCTs examining any form of non-surgical intervention against placebo, no treatment, sham treatment, or each other.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed eligibility, risk of bias, and extracted data. We performed meta-analyses when appropriate.

MAIN RESULTS

We included six trials (three in children, three in adults) with a total of 475 participants. We graded four trials at low risk of bias.Evidence from one trial (graded at low risk of bias) suggests that base-in prism reading glasses was no more effective than placebo reading glasses in improving clinical signs or symptoms in children.Evidence from one trial (graded at high risk of bias) suggests that base-in prism glasses using a progressive addition lens design was more effective than progressive addition lens alone in decreasing symptoms in adults. At three weeks of therapy, the mean difference in Convergence Insufficiency Symptoms Survey (CISS) score was -10.24 points (95% confidence interval (CI) -15.45 to -5.03).Evidence from two trials (graded at low risk of bias) suggests that outpatient (or office-based as used in the US) vision therapy/orthoptics was more effective than home-based convergence exercises (or pencil push-ups as used in the US) in children. At 12 weeks of therapy, the mean difference in change in near point of convergence, positive fusional vergence, and CISS score from baseline was 3.99 cm (95% CI 2.11 to 5.86), 13.13 diopters (95% CI 9.91 to 16.35), and 9.86 points (95% CI 6.70 to 13.02), respectively.In a young adult population, evidence from one trial (graded at low risk of bias) suggests outpatient vision therapy/orthoptics was more effective than home-based convergence exercises in improving positive fusional vergence at near (7.7 diopters, 95% CI 0.82 to 14.58), but not the other outcomes.Evidence from one trial (graded at low risk of bias) comparing four interventions, also suggests that outpatient vision therapy/orthoptics was more effective than home-based computer vision therapy/orthoptics in children. At 12 weeks, the mean difference in change in near point of convergence, positive fusional vergence, and CISS score from baseline was 2.90 cm (95% CI 0.96 to 4.84), 7.70 diopters (95% CI 3.94 to 11.46), and 8.80 points (95% CI 5.26 to 12.34), respectively. Evidence was less consistent for other pair-wise comparisons.

AUTHORS' CONCLUSIONS

Current research suggests that outpatient vision therapy/orthoptics is more effective than home-based convergence exercises or home-based computer vision therapy/orthoptics for children. In adult population, evidence of the effectiveness of various non-surgical interventions is less consistent.

[Treatment of non accomodated concomitant strabismus]

The aim of the study was comparative evaluation of surgical treatment and complex pre and postoperative pleoptic, orthoptic, diploptic treatment of non accommodated concomitant strabismus and identification of the optimum age for surgical treatment of strabismus. The 75 patients (from 2 to 10 years old) with manifested concomitant convergent strabismus were divided into two groups: patients operated at the age from 2 to 4 years old; patients operated at the age of 4-10 years). The 75 of patients operated at the age from 2 to 4 years old, which underwent orthoptic-diploptic treatment pre- and postoperatively got binocular vision showed the full recovery in only 40% of cases of the same age-group undergone the surgical treatment in combination with the direct occlusion. Binocular vision was achieved in 68% of patients operated at the age of 4-10 years with complex treatment, and in 25% in patients of the same age group with surgical treatment plus occlusion. The findings showed the efficacy of complex treatment as well as pre and postoperative pleoptic-orthoptic-diploptic treatment of strabismus and direct occlusion. Thus, the results of this study suggest that the delay of surgical treatment limits the ability to obtain optimal results.

Evidenced-based medicine: treatment for amblyopia

Amblyopia is defined as reduced and uncorrectable vision in a structurally normal eye. Early detection of amblyopia is very important. This can be accomplished through screening programs designed to identify amblyopia risk factors. Testing can be performed by trained teachers, technicians, school nurses and pediatricians as well as by eye care professionals. Once a child is identified as having an amblyopia risk factor it is crucial that the parents follow up with a pediatric ophthalmologist for a comprehensive examination. Amblyopia is the leading cause of monocular vision loss in the United States for adults under the age of 40. Amblyopia is amenable to therapy and is cost effective to treat. It is believed that earlier therapy for amblyopia provides better outcomes, but treatment has been shown effective even in some older children. In this paper, studies are cited regarding treatment of amblyopia.

Functional benefits of sensory and motor evaluation before strabismus surgery

Evaluating the sensory and motor status of your strabismus patient is an important part of the preoperative examination. However, not all clinicians follow the same protocol for this assessment. Many rely on personal experience to determine what tests to do. Is this enough? Interpreting the evidence regarding the proper preoperative exam for strabismus patients and incorporating it into your practice can help to enhance your postoperative results.

ROP: A cautionary tale: what we know and what we think we know

Retinopathy of prematurity is a complex disease with many subtleties and considerable individual variation. In order to obtain highly reliable evidence as to the nature of ROP, rigorous, randomized, controlled, multicenter trials that enroll a large number of eligible subjects are required. Fortunately, such trials have been conducted and have yielded a wealth of information. It is essential to critically evaluate these trials as well as other levels of scientific evidence to determine what our current state of knowledge is. This review focuses on what we know as fact and what may be common practice or empirical knowledge not based on rigorous evidence.

[Refractive laser eye surgery and binocular vision disorders--case report]

Laser refractive surgery is a lively developing branch of ophthalmology. There are a numbers of contraindications for this type of surgery, but many of them are difficult to define, for example binocular vision impairment. Accurate analysis of orthoptic examination before refractive surgery, has forced us to dissuade our patient from refractive surgery, despite the fact that there were no other contraindications.

CASE STUDY

A 33 years old woman referred for refractive surgery because of bilateral myopia (right eye: -5.25 Dsph -0.75 Dcyl ax. 170; left eye: -5.0 Dsph). There was no strabismus or other binocular vision disorders in her history. Orthoptic examination revealed exophoria, slight hyperphoria and considerable bilateral convergence insufficiency, which would have contributed to future strabismic complications.

Nonsurgical treatment for esotropia secondary to Arnold-Chiari I malformation: A case report

A 14-year-old girl with diplopia and esotropia secondary to Arnold-Chiari I malformation was surgically treated with Arnold-Chiari I malformation decompression (suboccipital craniectomy), C1 and partial C2 laminectomy, and duraplasty. The residual esotropia was treated with compensatory prisms and vision therapy more than 1 year after Arnold-Chiari malformation surgery. The esotropia was resolved after approximately 3.5 months of treatment. Five years later, the patient continued to maintain fusion without compensatory prism.

Children with low literacy and poor stereoacuity: an evaluation of complex interventions in a community-based randomized trial

PURPOSE

To assess, among children with low literacy and poor stereoacuity, the efficacy of two intervention programs on child vision and education compared to a control program.

METHODS

Eighty-eight children aged 8 to 13 years who had reading problems, and demonstrated poor stereoacuity as measured by the Titmus stereocircle test (> 100 seconds arc) or computerized assessment were randomized to one of two intervention programs: Lawson vision or Phono-Graphix, or a control group: Parental Literacy Support. Vision (Lang test, visual acuity, convergence insufficiency symptom survey) and education assessments (Woodcock Reading Mastery Tests-Revised) were conducted at baseline, intervention end (10 weeks), and 36 weeks. Analysis used intention to treat multi-level models.

RESULTS

Compared to the parental literacy support group, convergence insufficiency symptoms were reduced 36 weeks post-randomization amongst those receiving the Lawson orthoptic intervention (mean difference -5.55; 95% confidence interval (CI): -11.1 to -0.05, P < 0.05). Stereoacuity, measured by the Lang test, improved for both the Lawson and Phono-Graphix interventions compared to the parental literacy support group (-1.01; 95% CI: -1.6 to -0.4, P = 0.001, and -0.77; 95% CI: -1.4 to -0.2, P = 0.01). At the 36 week follow-up assessment, word identification had also improved for the Lawson and Phono-Graphix groups but other educational outcomes did not improve.

CONCLUSION

A formal randomized control trial was feasible in this setting. Intervention among children with poor stereoacuity and low literacy produced small improvements in stereopsis and convergence insufficiency symptom scores. Further randomized control trials should be conducted to clarify the role of orthoptic intervention on literacy in selected child populations.

Are Orthoptic Exercises an Effective Treatment for Convergence and Fusion Deficiencies?

PURPOSE

To investigate whether orthoptic exercises are an effective way to influence the near point of convergence, fusion range and asthenopic symptoms.

METHODS

Seventy-eight patients met the inclusion criteria of visual acuity 6/9 or better, no history of orthoptic treatment, squint surgery or Meares Irlen syndrome/dyslexia. Information was collected from case records related to diagnosis, near point of convergence, fusion range, prism and cover test measurements and symptoms. Type, duration and frequency of exercises were also recorded. Non-parametric statistics were applied.

RESULTS

Patients ranged in age from 5 to 73 years (mean 11.9). Females outnumbered males (46:32). The diagnoses were: decompensating heterophoria (n = 50) or convergence insufficiency (n = 28: primary 27; secondary 1). Exophoria was more common (n = 65), than esophoria (n = 11) or orthophoria (n = 1). Treatments were aimed at improving near point of convergence and/or reduced fusional reserves. The mean treatment period was 8.2 months. Reduced near point of convergence normalized following treatment in 47/55 cases, and mean near point of convergence improved from 16.6 to 8.4 cm (p = 0.0001). Fusional reserves normalized in 29/50. Fusional convergence improved significantly for those with exodeviation (p > 0.0006). Asthenopic symptoms improved in 65 patients. A reduction in deviation of 5 pd or more occurred in 20 patients.

CONCLUSIONS

Orthoptic exercises are an effective means of reducing symptoms in patients with convergence insufficiency and decompensating exophoria, and appear to target the proximal and fusional components of convergence. Their role in esophoria is unclear and needs further study.

Improving visual skills: II-remote assessment via Internet

BACKGROUND

Even though poor readers often have poor visual skills, such as binocular coordination and oculomotor control, students' visual skills are rarely assessed. Computer assessments have the potential to assist in identifying students whose visual skills are deficient. This study compared assessments made by an Internet-based computer orthoptics program with those of an on-site vision therapist.

METHODS

Students (N = 41) in grades 1 through 8, reading at least 2 levels below grade, were assessed for visual skill dysfunction (including binocular fusion and tracking ability) by a vision therapist at their school in Wisconsin. The therapist determined whether the student had adequate visual skills based on clinical and behavioral observations. A "remote" investigator located in California determined the adequacy of accommodative facility, tracking, and vergence skills in the same students, based on quantitative progress through the modules of an Internet-based computer orthoptics training program during 3 assessment sessions.

RESULTS

The on-site therapist made 33 referrals for possible visual skills training (80%). The remote investigator made 25 referrals (61%), all of which were consistent with referrals made by the on-site therapist; thus, no false-positives occurred when using the remote assessment technique. The 8 additional referrals by the therapist were attributed to the ability to observe student behavior during assessment.

CONCLUSIONS

Remote assessment of visual skills via an Internet orthoptics program may provide a simple means to detect visual skill problems experienced by poor readers.

[Therapeutic schedule in ambliopia--experience of Eye Clinic Cluj]

THE PURPOSE

To establlsh a protocol for the treatment of amblyopia and the methods used to maintain the results (visual acuity).

MATERIAL AND METHODS

Fifty children with amblyopia were treated in the Pediatric Ophthalmology Department of the Ophthalmological Cllnic in Cluj. Full time occlusion was used in all children. Pleoptic methods (Haidinger procedure, anti crowding fenomenon exercices and visual attention exercices) were done in the amblyopic children. The study analyzed the correlation of the visual acuity and the type of amblyopia (strabismic, anysometropic), the age of the patients and the age at the initiation of the treatment, the compliance. The visual acuity was followed up by check outs every 4-6 months.

RESULTS AND CONCLUSION

The study concluded that the treatment of choice in amblyopia is the full time occlusion. The partial occlusion and the optical penalization is reserved for the maintenance of the result (visual acuity) until the children reach the age of 7-8, when the sensitive period of visual development ends. The compliance of the children and parents is important. The hospitalization and the pleoptics used in a amlyopic children collectivity improve the children cooperation and the therapeutical results.

The effect of testing distance on the bielschowsky head tilt test

AIMS

The Bielschowsky Head Tilt Test (BHTT) is a commonly used test in Orthoptic practice and is used mainly to differentiate between a long standing Superior Oblique and Superior Rectus palsy. No consistent test distance is recommended in the literature and therefore the aim of this study was to determine whether test distance had an effect upon the measurements obtained.

METHOD

Thirteen participants were recruited. Participants had either longstanding or recent onset unilateral Superior Oblique palsy. Prism Cover Test measurements of the vertical angle of deviation were taken whilst the participant tilted their head to either side whilst fixating on a target at 33 cm, 3 m and 6 m.

RESULTS

The test distance does have a significant effect on the change in vertical angle measured with head tilted to either side (x2+7.747,DoF 2, p=0.021). When the median values are considered it appears that the significant effect occurs due to a smaller change in angle between head tilt to the affected side when fixing at 3 metres. This was confirmed using the Wilcoxon signed rank test (33cmv3m p=0.039, 3m v 6m p=0.013 and 33cm v 6m p=0.67).

CONCLUSIONS

The testing distance at which the BHTT is performed appears to have an effect upon the measurements obtained. The clinical importance of the difference in the change of angle with head tilt to either side is debatable due to the fact that the difference in the median measurement value between the three test distances is a maximum of 3 prism dioptres.

Randomized clinical trial of treatments for symptomatic convergence insufficiency in children

OBJECTIVE

To compare home-based pencil push-ups (HBPP), home-based computer vergence/accommodative therapy and pencil push-ups (HBCVAT+), office-based vergence/accommodative therapy with home reinforcement (OBVAT), and office-based placebo therapy with home reinforcement (OBPT) as treatments for symptomatic convergence insufficiency.

METHODS

In a randomized clinical trial, 221 children aged 9 to 17 years with symptomatic convergence insufficiency were assigned to 1 of 4 treatments.

MAIN OUTCOME MEASURES

Convergence Insufficiency Symptom Survey score after 12 weeks of treatment. Secondary outcomes were near point of convergence and positive fusional vergence at near.

RESULTS

After 12 weeks of treatment, the OBVAT group's mean Convergence Insufficiency Symptom Survey score (15.1) was statistically significantly lower than those of 21.3, 24.7, and 21.9 in the HBCVAT+, HBPP, and OBPT groups, respectively (P < .001). The OBVAT group also demonstrated a significantly improved near point of convergence and positive fusional vergence at near compared with the other groups (P

CONCLUSIONS

Twelve weeks of OBVAT results in a significantly greater improvement in symptoms and clinical measures of near point of convergence and positive fusional vergence and a greater percentage of patients reaching the predetermined criteria of success compared with HBPP, HBCVAT+, and OBPT. Application to Clinical Practice Office-based vergence accommodative therapy is an effective treatment for children with symptomatic convergence insufficiency.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00338611.

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Key Words

• convergence insufficiency
• asthenopia
• vision therapy
• orthoptics
• vergence/accommodative therapy
• pencil push-ups
• computer vergence/accommodative therapy
• placebo therapy
• exophoria
• eyestrain
• symptom survey

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MESH Headings

• Adolescent
• Child
• Confidence Intervals
• Convergence, Ocular
• Female
• Home Nursing
• Humans
• Male
• Multivariate Analysis
• Ocular Motility Disorders/diagnosis
• Ocular Motility Disorders/therapy
• Office Visits
• Ophthalmology/methods
• Orthoptics/methods
• Patient Compliance
• Probability
• Recovery of Function
• Reference Values
• Sensitivity and Specificity
• Severity of Illness Index
• Strabismus/diagnosis
• Strabismus/therapy
• Treatment Outcome
• Vision, Binocular
• Visual Acuity

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Grants

• U10 EY014712 NEI NIH HHS
• U10 EY014676-02 NEI NIH HHS
• U10 EY014712-04 NEI NIH HHS
• U10 EY014659-03 NEI NIH HHS
• U10 EY014676-01A1 NEI NIH HHS
• U10 EY014713-01A2 NEI NIH HHS
• U10 EY014713-02 NEI NIH HHS
• U10 EY014715-01A1S1 NEI NIH HHS
• U10 EY014716-04 NEI NIH HHS
• U10 EY014710-04 NEI NIH HHS
• U10 EY014676 NEI NIH HHS
• U10 EY014706-01A1S1 NEI NIH HHS
• U10 EY014713 NEI NIH HHS
• U10 EY014709 NEI NIH HHS
• U10 EY014659-01A2 NEI NIH HHS
• U10 EY014715-04 NEI NIH HHS
• U10 EY014712-01A1 NEI NIH HHS
• U10 EY014713-03 NEI NIH HHS
• U10 EY014706-01A1 NEI NIH HHS
• U10 EY014715-02 NEI NIH HHS
• U10 EY014709-03 NEI NIH HHS
• U10 EY014715-03 NEI NIH HHS
• U10 EY014676-04 NEI NIH HHS
• U10 EY014715 NEI NIH HHS
• U10 EY014716-03 NEI NIH HHS
• U10 EY014710-02 NEI NIH HHS
• U10 EY014709-04 NEI NIH HHS
• U10 EY014716-02 NEI NIH HHS
• U10 EY014716-02S1 NEI NIH HHS
• U10 EY014706-02 NEI NIH HHS
• U10 EY014713-04 NEI NIH HHS
• U10 EY014709-02 NEI NIH HHS
• U10 EY014712-03 NEI NIH HHS
• U10 EY014706-04 NEI NIH HHS
• U10 EY014710-01A1S1 NEI NIH HHS
• U10 EY014710-01A1 NEI NIH HHS
• U10 EY014659-04 NEI NIH HHS
• U10 EY014676-03 NEI NIH HHS
• U10 EY014712-01A1S1 NEI NIH HHS
• U10 EY014659-02 NEI NIH HHS
• U10 EY014676-01A1S1 NEI NIH HHS
• U10 EY014716-01A1 NEI NIH HHS
• U10 EY014709-01A1 NEI NIH HHS
• U10 EY014706-03 NEI NIH HHS
• U10 EY014716-01A1S1 NEI NIH HHS
• U10 EY014716 NEI NIH HHS
• U10 EY014715-01A1 NEI NIH HHS
• U10 EY014709-01A1S1 NEI NIH HHS
• U10 EY014712-02 NEI NIH HHS
• U10 EY014710-03 NEI NIH HHS
• U10 EY014659 NEI NIH HHS

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The convergence insufficiency treatment trial: design, methods, and baseline data

OBJECTIVE

This report describes the design and methodology of the Convergence Insufficiency Treatment Trial (CITT), the first large-scale, placebo-controlled, randomized clinical trial evaluating treatments for convergence insufficiency (CI) in children. We also report the clinical and demographic characteristics of patients.

METHODS

We prospectively randomized children 9 to 17 years of age to one of four treatment groups: 1) home-based pencil push-ups, 2) home-based computer vergence/accommodative therapy and pencil push-ups, 3) office-based vergence/accommodative therapy with home reinforcement, 4) office-based placebo therapy. Outcome data on the Convergence Insufficiency Symptom Survey (CISS) score (primary outcome), near point of convergence (NPC), and positive fusional vergence were collected after 12 weeks of active treatment and again at 6 and 12 months posttreatment.

RESULTS

The CITT enrolled 221 children with symptomatic CI with a mean age of 12.0 years (SD = +2.3). The clinical profile of the cohort at baseline was 9Delta exophoria at near (+/- 4.4) and 2Delta exophoria (+/-2.8) at distance, CISS score = 30 (+/-9.0), NPC = 14 cm (+/- 7.5), and near positive fusional vergence break = 13 Delta (+/- 4.6). There were no statistically significant nor clinically relevant differences between treatment groups with respect to baseline characteristics (p > 0.05).

CONCLUSION

Hallmark features of the study design include formal definitions of conditions and outcomes, standardized diagnostic and treatment protocols, a placebo treatment arm, masked outcome examinations, and the CISS score outcome measure. The baseline data reported herein define the clinical profile of those enrolled into the CITT.

Amblyopia and Strabismus Questionnaire (A&SQ): clinical validation in a historic cohort

BACKGROUND

We recently developed the Amblyopia & Strabismus Questionnaire (A&SQ) to assess the quality of life in amblyopia and/or strabismus patients, and evaluated its content and criterion validity. The A&SQ was now validated clinically by correlating its outcome with past and current orthoptic parameters in a historic cohort of amblyopia and/or strabismus patients.

METHODS

The cohort was derived from all 471 patients who were treated by occlusion therapy in the Waterland Hospital in Purmerend between 1968 and 1974 and born between 1962 and 1972. All children with insufficient visual acuity from the Waterland area had been referred to a single ophthalmologist and orthoptist. Of these, 203 were traced, and 174 filled out the A&SQ. In 137 of these, binocular vision, visual acuity, and angle of strabismus were reassessed 30-35 years after occlusion therapy. These clinical parameters were correlated with the five A&SQ domains: "distance estimation", "visual disorientation", "fear of losing the better eye", "diplopia", and "social contact and cosmetic problems".

RESULTS

The current acuity at distance of the amblyopic eye and reading acuity of the amblyopic eye correlated significantly with all five A&SQ domains (significance level P = 0.01-P = 0.05). Weaker correlations were found for binocularity. In spite of the expectation that stereopsis should strongly correlate with the domain "distance estimation", and angle of strabismus with the domain "social contact and cosmetic problems", the acuity of the amblyopic eye was the overall dominant parameter.

CONCLUSIONS

The adult acuity of the amblyopic eye seems the most important clinical determinant for quality of life in amblyopia and/or strabismus patients, even in domains of distance estimation, visual disorientation, and social contact and cosmetic problems, although intermediate determinants cannot be excluded.

Contrast sensitivity function and ocular higher-order aberrations following overnight orthokeratology

PURPOSE

To evaluate relationships among contrast sensitivity function, ocular higher-order aberration, and myopic correction in eyes undergoing overnight orthokeratology for myopia.

METHODS

A prospective study was conducted in 46 eyes of 23 patients undergoing orthokeratology. Inclusion criteria were spherical equivalent refraction between -1.00 and -4.00 diopters (D), refractive astigmatism up to 1.00 D, and best-corrected visual acuity of 20/20 or better. Ocular higher-order aberrations and contrast sensitivity function were determined before and 3 months after initiation of the procedure. We measured three indices of contrast sensitivity function: contrast sensitivity, low-contrast visual acuity, and letter contrast sensitivity with the CSV-1000 charts (Vector Vision Co., Greenville, OH). Area under the log contrast sensitivity function (AULCSF) was calculated from the contrast sensitivity data.

RESULTS

Orthokeratology significantly improved logMAR uncorrected visual acuity (P < 0.0001; paired t-test) but significantly increased ocular higher-order aberrations (P < 0.0001) and decreased contrast sensitivity function, including AULCSF (P < 0.0001), low-contrast visual acuity (P = 0.0025), and letter contrast sensitivity (P < 0.0001; Wilcoxon signed-rank test). The induced changes in AULCSF, low-contrast visual acuity, and letter contrast sensitivity by orthokeratology showed significant correlation with changes in third-order (Pearson r = -0.430, P = 0.0026; r = 0.423, P = 0.0031; and Spearman r(s) = -0.351, P = 0.0186, respectively), fourth-order (r = -0.418, P = 0.0035; r = 0.425, P = 0.0029; and r(s) = -0.566, P = 0.0001, respectively), and total higher-order (r = -0.460, P = 0.0011; r = 0.471, P = 0.0008; and r(s) = -0.434, P = 0.0036, respectively) aberrations. The induced changes in contrast sensitivity function and higher-order aberrations significantly correlated with the amount of myopic correction (P < 0.01).

CONCLUSIONS

Orthokeratology significantly increases ocular higher-order aberrations and compromises contrast sensitivity function, depending on the amount of myopic correction.

Optical Quality of the Cornea After Overnight Orthokeratology

PURPOSE

To review changes in the optical quality of the cornea induced by overnight orthokeratology for myopia.

METHODS

Sixty-four eyes of 39 patients who underwent overnight orthokeratology for myopia were prospectively examined. Inclusion criteria were uncorrected visual acuity of 20/20 or better after treatment and a minimum follow-up of 3 months. To quantitatively assess changes in corneal regular and irregular astigmatism, videokeratography data were decomposed into spherical component, regular astigmatism, asymmetry, and higher-order irregularity using Fourier analysis. In addition, corneal wavefront aberrations were calculated by expanding anterior corneal height data from videokeratography into a set of orthogonal Zernike polynomials.

RESULTS

Although orthokeratology significantly reduced manifest refraction and improved uncorrected visual acuity, the asymmetry component, which is one of the features of irregular astigmatism, increased significantly from 0.35 +/- 0.22 to 0.64 +/- 0.40 D after treatment (P < 0.0001, paired t test). The increases in the asymmetry component significantly correlated with the amount of myopic correction (Pearson correlation coefficient, R = 0.40, P = 0.0009). Furthermore, the root-mean-square of third-order (coma-like) and fourth-order (spherical-like) aberrations significantly increased after orthokeratology (P < 0.0001, paired t test), and these increases showed significant positive correlations with the amount of myopic correction (Pearson correlation coefficient, R = 0.452, P = 0.0001 and R = 0.381, P = 0.0017, respectively).

CONCLUSION

Corneal irregular astigmatism and higher-order aberrations significantly increased even in clinically successful orthokeratology, and the increases correlated with the magnitude of myopic correction. A large myopic correction by orthokeratology should be avoided to not decrease corneal optical quality.