Features

Truth or myth: The preferred sighting method is the best way of measuring ocular dominance?

Contact Lenses Practice
This month, in our series looking at common myths concerning contact lenses, Junghee Seo and Kurt Moody look at whether the preferred sighting method is a good place to start

Soft contact lens options for presbyopes include monovision and multifocal (MF) contact lenses (CLs). An international CL prescribing survey conducted in 2022 reported that these two lens modalities accounted for 21% of all soft contact lens fittings.1 

Looking specifically at presbyopic contact lens wearers, 53% were fit in MF and 7% in monovision lenses.1 An interesting comparison would be the country difference; the US mix is 30% multifocal and 31% monovision, whereas Greece is 80% multifocal and 0% monovision.1  

When fitting monovision contact lenses, the dominant eye is optimally corrected for distance and the non-dominant eye for near. At times, to extend the depth of focus with MF lenses, the fitter will add plus power, thereby inducing disparity, to the non-dominate eye to optimise near vision.  

It has been noted that as the amount of disparity increases, binocular summation decreases and this decrease can be even greater when it is applied to the dominant versus the non-dominant eye.2  

Thus, determination of ocular dominance is an important component to assess during presbyopic contact lens fittings. 

  

Professional Belief Survey Results 

A recent survey of 1,028 eye care professionals (ECPs) conducted in 2021 in Russia and in 2022 for the other markets, assessed the prescribing beliefs of ECPs. This survey reported that on average, 61% of eye care practitioners used the preferred sighting method to determine ocular dominance.3 This method was largely used by all the markets surveyed, as shown below.3 

  

 

What the Evidence Shows 

Preferred sighting, also known as the hole-in-card method, is a type of motor ocular dominance test typically conducted using the patient’s hands. Some publications report that it is the preferred method used to determine ocular dominance as it is quick and simple.4, 5  

However, most MF contact lens manufacturers’ guidelines, as well as other publications,4,6 recommend using the blur test to achieve a successful fitting. This is a sensory ocular dominance test that uses a +1.00DS or +1.50DS lens over each eye under binocular viewing conditions to evaluate ocular dominance.  

The blur test is preferred as it provides a more accurate representation of presbyopic viewing conditions, as it simulates the addition of disparity and determines which eye has the greater sensitivity to plus defocus.4-6  

Studies comparing the preferred sighting and blur tests have found ocular dominance agreement to range from only 40% to 52.3% among presbyopes4, 6 and 50% to 58% among non-presbyopes.5, 6 Therefore, there is no clinical correlation among these two types of tests.5-7

In fact, one study found a statistically significant difference in dominance where 71% and 54% of the same subjects were determined to be right eye dominant by the preferred sighting test and blur test, respectively.6  

Thus, the use of both sighting and sensory ocular dominance tests to measure dominance is not recommended due to the variability between them. It has been demonstrated that, even among different tests of motor ocular dominance, there is low to moderate agreement.8  

  

Conclusions 

While commonly used by practitioners, the preferred sighting technique may not be an accurate measure of true ocular dominance as it can vary depending on the angle of gaze.9  

In one study, subjects demonstrated a reversal in ocular dominance when the horizontal gaze angle was 15.5° away from primary gaze.9 Ocular dominance can also vary depending on factors like attention level and testing conditions.10  

The blur test can mitigate many of these disadvantages as it is conducted with both eyes open and simulates the addition of disparity and is therefore the most commonly recommended and preferred test for successful MF CL fitting.4,6  

  • Dr Junghee Seo is a Clinical Associate at the Centre for Ocular Research & Education, School of Optometry & Vision Science, University of Waterloo.
  • Dr. Kurt Moody is Director of Professional Education North America for Johnson & Johnson Vision Care, Inc. 

  

References 

  1. Morgan PB, Woods CA, Tranoudis IG, et al. International contact lens prescribing in 2022. Contact Lens Spectrum. 2023; 38: 28-35. 
  2. Pardham S, Gilchrist J. The effect of monocular defocus on binocular contrast sensitivity. Ophthal. Physiol. Opt. 1990; (10): 33-36. 
  3. Johnson & Johnson Vision Care. Online survey of 1028 Eye Care Professionals across United States, United Kingdom, Russia, China, Japan and South Korea. Data on file 2021 (Russia) and 2022 (other markets). 
  4. Evans BJ. Monovision: a review. Ophthal. Physiol Opt. 2007; 27(5): 417-439. 
  5. Seijas O, Gómez de Liaño P, Gómez de Liaño R, Roberts CJ, Piedrahita E, Diaz E. Ocular dominance diagnosis and its influence in monovision. Am J Ophthalmol. 2007; 144(2): 209-216. 
  6. Pointer JS. Sighting versus sensory ocular dominance. J Optom. 2021; 5: 52-55. 
  7. Lopes-Ferreria D, Neves H, Queiros A, Faria-Riberio M, Peixoto-de-Matos SC, González-Méijome JM. Ocular dominance and visual function testing. Biomed Res Int. 2013; Article ID 238943. 
  8. Rice ML, Leske DA, Smestad CE, Holmes JM. Results of ocular dominance testing depend on assessment method. J AAPOS. 2008; 12(4): 365-369. 
  9. Khan AZ, Crawford JD. Ocular dominance reverses as a function of horizontal gaze angle. Vision Research. 2001; 41: 1743-1748.  
  10. Ooi TL, He ZJ. Binocular rivalry and visual awareness: the role of attention. Perception. 1999; 28: 551-574.