4.1.7 Manages non-tolerance cases

What are the signs for psychological non-tolerance?

• Irregular symptoms that fail to fit any pattern

• Apparent determination to simply ‘not get on’ with their new spectacles

What are the potential reasons for psychological non-tolerance?

• Patient feels they were forced into the purchase

• Upon reflection they didn’t want to spend that much

• They have changed their mind about the style of frame chosen

• A third party has made an unfavourable comment about their new spectacles

• The spectacle lens solution chosen does not fit into the patient’s lifestyle

• The spectacles fail to meet with the patient’s expectations

- Even if you suspect a patient is psychologically rejecting their spectacles, you must still eliminate any chance of actual lens intolerance

What checks should be carried out when investigating single vision and bifocal spectacle non-tolerance?

SV spectacles:

• Focimeter and confirm sphere/cyl/axis

• Check optical centres align with measured PDs

• Check coating/tints

• Check frame fitting

Bifocals = as for single vision but also:

• Check near add power and whether sufficient for requirements

• Check fitting (i.e. segment height and inset) and segment choice

What additional checks should be carried out when investigating progressive spectacle non-tolerance?

• Check near add power and whether sufficient for requirements

• Check frame depth to ensure patient can achieve maximum add

• Check fitting (i.e. fitting cross heights, mono PD) and choice of lens design

• Consider patient adaptation periods/education on how to use their lenses

What should be considered when investigating refraction and optical centration errors in spectacle non-tolerance?

Refraction

• Recheck

• Consider cycloplegic refraction, any change in cylinder, and refractive change (e.g. cataract)

Optical centration errors

• Unwanted prismatic effect (remember P = cF).

• Prism increases with error in centration or power of the lens

How can changes in lens form and lens material contribute to spectacle non-tolerance?

• A common change in lens form is spherical to aspherical

• Aspheric lenses pose possibly the biggest risk for potential single vision intolerance and although their design overcomes the poor off axis performance that occurs in some spherical forms, some wearers just will not tolerate them.

• A wearer that has adapted to the off-axis performance of a spherical lens will often find the sudden change experienced when they are switched to an aspheric lens form difficult to adapt to

What are the possible causes of progressive spectacle non-tolerance?

• Ineffective instruction as to their use

• Inappropriate change in design of progressive

• Inappropriate lens design

• Incorrect positioning

• Non-tolerance to progressive lenses could be simply down to the patient not understanding how to use them

• Our role dictates that we must ensure every new progressive wearer understands how to use their new lenses (even if this takes up a whole morning in the practice!)

How can progressive lens non-tolerance be prevented when prescribing and dispensing new spectacles?

• Ensure each new wearer understands how to use their new spectacles

• Avoid unnecessary changes in lens brand/lens design

• To avoid the risk of intolerance to a different lens brand/design, often the best action to take is not to change it in the first place. If the wearer is happy with their current design, keep to it and only consider a change for very good reasons

• If changing lens design ensure you discuss this carefully with the patient and make sure they understand that a process of adaptation may be required

How can short corridor lenses and incorrect positioning contribute to progressive spectacle non-tolerance?

• For both new and existing wearers that require a good field of view for intermediate or close work the use of a short corridor lens may result in non-tolerance.

• Symptoms of this are commonly an inability to view a computer screen and complaining they can only read through a tiny portion of the lens.

• Incorrect positioning of a progressive lens may also result in non-tolerance if this is not quickly identified and if possible rectified during the collection