Myopia Research

 



Al-Bdour MD, Odat TA, Tahat AA. "Myopia and level of education." Eur J Ophthalmol, 2001 Jan-Mar; 11(1):1-5
    Purpose: To find out whether the development of myopia is related to the level of education. Methods: From two big ophthalmic outpatient clinics in Jordan, 968 subjects (between the age of 24 and 45 years) were included in this study. A subject was considered myopic if at least one eye had a spherical equivalent refractive error of at least -0.75 diopter. The subjects were divided into two groups: the educated group was those who had finished at least 12 years of education and the non-educated which included those with maximum of six years of education. There were 468 men and 500 women. Results: The frequency of myopia was higher in the educated group in both men and women. A significant relationship was found between the level of education and myopia in the whole study group (p<0.0001). Conclusions: This study had too few subjects to draw general conclusions, but within the study group there was a significant relationship between the level of education and the development of myopia.
 
Alller T, Grisham JD, "Myopia Progression Control Using Bifocal Contact Lenses." Optometry and Vision Science, 2000. 77(12s): p. 187.
     The study of 84 myopic people (age 9 to 40) using traditional single vision spectacles, progressive addition lenses, single vision soft contact lenses, and bifocal soft contact lenses found about -0.50 D increase in myopia with single vision soft contacts or spectacles, -0.37D with progressive addition lenses and -0.08 D (p<0.0001) with bifocal soft contact lens.  Soft bifocal contact lenses are indicated to slow the progression of myopia.
 
Bobier WR, Sivak JG. "Orthoptic treatment of subjects showing slow accommodative responses."  Am J Optom Physiol Opt, 60:678-87, 1983.
    Abstract: Five subjects showing slow accommodative responses were given optometric vision therapy. Speed of accommodative response improved after 3 to 6 weeks.  No regressions were evident 18 weeks after the cessation of training.  The results of the study indicate that optometric vision therapy is effective in improving slow accommodative responses.
 

Cheng D., Schmid K., Woo G., Drobe B."Randomized Trial of Effect of Bifocal and Prismatic Bifocal Spectacles on Myopic Progression"  Arch Ophthalmol. 2010;128(1):12-19.

      Objective  To determine whether bifocal and prismatic bifocal spectacles could control myopia in children with high rates of myopic progression.

     Methods  This was a randomized controlled clinical trial. One hundred thirty-five (73 girls and 62 boys) myopic Chinese Canadian children (myopia of 1.00 diopters [D]) with myopic progression of at least 0.50 D in the preceding year were randomly assigned to 1 of 3 treatments: (1) single-vision lenses (n = 41), (2) +1.50-D executive bifocals (n = 48), or (3) +1.50-D executive bifocals with a 3–prism diopters base-in prism in the near segment of each lens (n = 46).

      Main Outcome Measures  Myopic progression measured by an automated refractor under cycloplegia and increase in axial length (secondary) measured by ultrasonography at 6-month intervals for 24 months. Only the data of the right eye were used.

      Results  Of the 135 children (mean age, 10.29 years [SE, 0.15 years]; mean visual acuity, –3.08 D [SE, 0.10 D]), 131 (97%) completed the trial after 24 months. Myopic progression averaged –1.55 D (SE, 0.12 D) for those who wore single-vision lenses, –0.96 D (SE, 0.09 D) for those who wore bifocals, and –0.70 D (SE, 0.10 D) for those who wore prismatic bifocals. Axial length increased an average of 0.62 mm (SE, 0.04 mm), 0.41 mm (SE, 0.04 mm), and 0.41 mm (SE, 0.05 mm), respectively. The treatment effect of bifocals (0.59 D) and prismatic bifocals (0.85 D) was significant (P < .001) and both bifocal groups had less axial elongation (0.21 mm) than the single-vision lens group (P < .001).

      Conclusions  Bifocal lenses can moderately slow myopic progression in children with high rates of progression after 24 months.

      Applications to Clinical Practice  Bifocal spectacles may be considered for slowing myopic progression in children with an annual progression rate of at least 0.50 D.


 
Culhane HM, Winn B. "Dynamic Accommodation and Myopia." Invest. Ophthalmol. Vis. Sci. 1999 40: 1968-1974.
    Purpose: Accommodative effort during nearwork is thought to be a causative factor in the development of myopia. It has been proposed that an anomaly in autonomic control may be a precursor to the development of myopia. In the present study the closed-loop accommodation response after variations in fixation period was investigated in emmetropes, early-onset myopes and late-onset myopes to determine characteristics of reflex accommodation for each refractive group.   
    Methods: Closed-loop accommodation responses were measured in a group of emmetropes (n = 7), early-onset myopes (n = 7), and late-onset myopes (n = 7) by use of a dynamic tracking infrared optometer. A variation in fixation period (10 seconds, 60 seconds, and 180 seconds) before an accommodative step was used to stimulate the accommodation control mechanism differentially.  
    Results: Group results of accommodative response times showed that late-onset myopes were significantly affected by the duration of fixation before the change in stimulus vergence. Accommodative response times after 3 minutes of sustained near vision were significantly longer than those observed for other groups for the near-to-far condition. Reaction time appears to be independent of refractive grouping, prior fixation period, and direction of step change. 
    Conclusions: Late-onset myopes showed significantly extended accommodation response times after a sustained near vision task that was demonstrable under well-controlled experimental conditions. The extended response times observed in the present study were consistent with previous reports of refractive shifts in late-onset myopes and early-onset myopes and provide a corollary between reflex and adaptive components of the accommodation response. Potential mechanisms are discussed in an attempt to explain the resultant hysteresis under closed-loop viewing conditions
 
Jiang BC, Bussa S, Tea YC, Seger K.  "Optimal dioptric value of near addition lenses intended to show myopic progression."  Optom Vis Sci. 85(11):1100-5, 2008. 

   Purpose: The purpose of this study was to determine the optimal power value of near addition lenses, which would create the least error in accommodative and vergence responses.
   Methods: We evaluated accommodative response, phoria, and fixation disparity when the subject viewed through various addition lenses at three working distances for 30 young adults (11 emmetropic, 17 myopic, and 2 hyperopic). Accommodative response was determined with a Canon R-1 infrared optometer under binocular viewing conditions, phoria was determined by the alternating cover test with prism neutralization, and fixation disparity was measured with a Sheedy disparometer.
   Results: We found that the optimal powers of near addition lenses for the young adult subjects associated with zero retinal defocus were +0.92 D, +1.04 D, and +1.28 D at three viewing distances, 50 cm, 40 cm, and 30 cm, respectively. The optimal powers associated with -3 prism diopters (Delta) near phoria were +0.58 D, +0.35 D, and +0.20 D at the three distances, 50 cm, 40 cm, and 30 cm, respectively. In addition, we found high correlations between the initial accommodative error and the optimal power of the near addition lenses and between the initial near phoria and the optimal power of the near addition lenses.
   Conclusions: The results suggest that when the effects of near addition lenses on the accommodative and vergence systems are both considered, the optimal dioptric power of the near addition lens is in a range between +0.20 D and +1.28 D for the three viewing distances. Using progressive lenses to delay the progression of myopia may have promising results if each subject's prescription is customized based on establishing a balance between the accommodative and vergence systems. Formulas derived from this study provide a basis for such considerations.


London R, Wick B, Kirschen D. "Post-Traumatic Pseudomyopia." Optometry. 2003 Feb;74(2):111-20.
    Background: Many clinicians have noted that patients demonstrate a myopic refractive change following Traumatic Brain Injury (TBI).  This apparent myopic shift disappears with cycloplegia, yet stubbornly reappears as soon as the pharmaceutical effect wears off.  We propose that this shift is secondary to an irritative lesion that affects the parasympathetic innervation, resulting in ciliary body contracture.  The dilemma for the clinician is whether to provide the immediate relief of clear distance vision by prescribing additional minus lenses, or to work toward attempting to re-establish the baseline refractive error. 
    Case Reports: The natural history of post-traumatic pseudomyopia in our experience involves one of the following three courses: (1) a transient condition that will occasionally resolve; (2) the typical case, a recalcitrant condition that will resolve under cycloplegic intervention, but immediately return as the cycloplegic wears off; or (3) a less-common subgroup of patients who continue to show an increase in myopia over time. Our description of these cases demonstrates management strategies (including atropinization) to relax accommodative spasm, traditional vision therapy techniques aimed at loosening the accommodative system, and refractive corrections. 
    Conclusions: Pseudomyopia is one of many ocular and behavioral sequelae following TBI. By understanding the natural course and potential management options for post-traumatic pseudomyopia, the clinician will be better prepared to deal with these challenging cases.  Flexibility is required, since options that work with one patient may prove ineffective with another.  Counseling the patient as to potential outcomes given the natural history of this condition helps establish more-realistic expectations by the patients being treated.

 
Vitale S, Sperduto R, Ferris III F, "Increased prevalence of myopia in the United States between 1971-1972 and 1999-2004." Arch Ophthalmol. 2009;127(12):1632-1639. 
   Objective: To compare US population prevalence estimates for myopia in 1971-1972 and 1999-2004.
   Methods: The 1971-1972 National Health and Nutrition Examination Survey provided the earliest nationally representative estimates for US myopia prevalence; myopia was diagnosed by an algorithm using either lensometry, pinhole visual acuity, and presenting visual acuity (for presenting visual acuity 20/40) or retinoscopy (for presenting visual acuity 20/50). Using a similar method for diagnosing myopia, we examined data from the 1999-2004 National Health and Nutrition Examination Survey to determine whether myopia prevalence had changed during the 30 years between the 2 surveys.
   Results: Using the 1971-1972 method, the estimated prevalence of myopia in persons aged 12 to 54 years was significantly higher in 1999-2004 than in 1971-1972 (41.6% vs 25.0%, respectively; P.001). Prevalence estimates were higher in 1999-2004 than in 1971-1972 for black individuals (33.5% vs 13.0%, respectively; P.001) and white individuals (43.0% vs 26.3%, respectively; P.001) and for all levels of myopia severity (2.0 diopters [D]: 17.5% vs 13.4%, respectively [P.001];2.0 to 7.9 D: 22.4% vs 11.4%, respectively [P.001]; 7.9 D: 1.6% vs 0.2%, respectively [P.001]).
   Conclusions: Whenusing similarmethodsforeachperiod, the prevalence of myopia in the United States appears to be substantiallyhigherin1999-2004than30years earlier.Identifying modifiable risk factors for myopia could lead to the development of cost-effective interventional strategies.
 
Wolffsohn JS, Gilmartin B, Thomas R, Mallen EA. "Refractive error, cognitive demand and nearwork-induced transient myopia." Curr Eye Res. 2003 Dec;27(6):363-70.
    Purpose: Whereas many previous studies have identified the association between sustained near work and myopia, few have assessed the influence of concomitant levels of cognitive effort. This study investigates the effect of cognitive effort on near-work induced transient myopia (NITM).
    Methods: Subjects comprised of six early onset myopes (EOM; mean age 23.7 yrs; mean onset 10.8 yrs), six late-onset myopes (LOM; mean age 23.2 yrs; mean onset 20.0 yrs) and six emmetropes (EMM; mean age 23.8 yrs). Dynamic, monocular, ocular accommodation was measured with the Shin-Nippon SRW-5000 autorefractor. Subjects engaged passively or actively in a 5 minute arithmetic sum checking task presented monocularly on an LCD monitor via a Badal optical system. In all conditions the task was initially located at near (4.50 D) and immediately following the task instantaneously changed to far (0.00 D) for a further 5 minutes. The combinations of active (A) and passive (P) cognition were randomly allocated as P:P; A:P; A:A; P:A.
    Results: For the initial near task, LOMs were shown to have a significantly less accurate accommodative response than either EOMs or EMMs (p < 0.001). For the far task, post hoc analyses for refraction identified EOMs as demonstrating significant NITM compared to LOMs (p < 0.05), who in turn showed greater NITM than EMMs (p < 0.001). The data show that for EOMs the level of cognitive activity operating during the near and far tasks determines the persistence of NITM; persistence being maximal when active cognition at near is followed by passive cognition at far.
    Conclusions: Compared with EMMs, EOMs and LOMs are particularly susceptible to NITM such that sustained near vision reduces subsequent accommodative accuracy for far vision. It is speculated that the marked NITM found in EOM may be a consequence of the crystalline lens thinning shown to be a developmental feature of EOM. Whereas the role of small amounts of retinal defocus in myopigenesis remains equivocal, the results show that account needs to be taken of cognitive demand in assessing phenomena such as NITM.
 
Wolffsohn B, Gilmartin B, Wing-hong Li R, Hastings Edwards M,  Wing-shan Chat S, Kwok-fai Lew J,  Sin-ying Yu, B. "Nearwork-Induced Transient Myopia in Preadolescent Hong Kong Chinese."  Investigative Ophthalmology and Visual Science. 2003;44:2284-2289.
    Purpose: To compare the magnitude and time course of nearwork-induced transient myopia (NITM) in preadolescent Hong Kong Chinese myopes and emmetropes.  
    Method: Forty-five Hong Kong Chinese children, 35 myopes and 10 emmetropes aged 6 to 12 years (median, 7.5), monocularly viewed a letter target through a Badal lens for 5 minutes at either 5.00- or 2.50-D accommodative demand, followed by 3 minutes of viewing the equivalent target at optical infinity. Accommodative responses were measured continuously with a modified, infrared, objective open-field autorefractor. Accommodative responses were also measured for a countercondition: viewing of a letter target for 5 minutes at optical infinity, followed by 3 minutes of viewing the target at a 5.00-D accommodative demand. The results were compared with tonic accommodation and both subject and family history of refractive error.  
    Results: Retinal-blur-driven NITM was significantly greater in Hong Kong Chinese children with myopic vision than in the emmetropes after both near tasks, but showed no significant dose effect. The NITM was still evident 3 minutes after viewing the 5.00-D near task for 5 minutes. The magnitude of NITM correlated with the accommodative drift after viewing a distant target for more than 4 minutes, but was unrelated to the subjects or family history of refractive error. 
    Conclusions: In a preadolescent ethnic population with known predisposition to myopia, there is a significant posttask blur-driven accommodative NITM, which is sustained for longer than has previously been found in white adults.