latent hyperopia Flashcards
what is a side effect of dilantin
can affect the EOMs
manifest hyperopia
the amount of hyperopia that is found on subjective refraction
latent hyperopia
the remaining hyperopia compensated for by the tonicity of the CB (cyclo hyperopia)
absolute hyperopia
the amount of hyperopia that cannot be overcome by accommodation (Add)
facultative hyperopia
the amount of hyperopia that can be overcome by accommodation. for example if a patient has 4.00D of hyperopia and only 1.00D of accommodation, the absolute hyperopia is 3.00D and facultative hyperopia is 1.00D
with accommodation
if a 10yo patient with CC of headaches when reading has +0.50 OU on refraction and +2.00 OU on cycloplegic refraction, what is the best initial RX
+2.00 OU for reading only
the patients chief complaint is reading, therefore the full cyclo will allow for normal accommodative demand at near and will likely alleviate the patient’s asthenopia symptoms
+2.00 full time wear would not be recommended because this would blur the child for distance. she does not have any accommodative ET, if so, this RX would be required
+0.50 for reading only is likely not enough plus
+0.50 for distance only is not correct bc she is not complaining of distance blur
no glasses is not an option bc she is symptomatic and school performance is suffer
+2.00D for distance only is not good bc see above
dynamic retinoscopy
objective measure of the accommodative response at near
examples are MEM, and Notts method
MEM
performed with the patient wearing dry distance refraction while focusing on a near target on the ret head. the dr uses a vertical ret stark to look for with or against motion
with motion on MEM
lag of accommodation (if you have to add plus)
against motion on MEM
lead of accommodation (If you have to add minus)
a lead on MEM will be ___number
minus
a lag on MEM with be ___numbers
plus
what must you be careful with in latent hyperopes
don’t over plus them at distance
patients who have to accommodate to see the distance will likely have a higher _____ of accommodation
lag
what does distance do for convergence
adds convergence
normal MEM
+0.25 to +0.50 (small lag)
abnormal MEM
> +0.50 or any minus
things that warrant a cycloplegic refraction
suspicion of latent hyperopia
suspicion of pseudomyopia
accommodative ET or EP
variable retinoscopy or refraction findings
VA not at expected level
symptoms do not seem to be related to manifest eye strain
what is the far point for a patient who wears +2.00D glasses at a vertex distance of 15mm?
48.5cm behind the cornea
when a patient has been optically corrected for ametropia, the far point of the eye will coincide with the secondary focal point of the correcting lens. for hyperopes, the far point is considered virtual (behind the eye), while for a myope, the far point is real (in front of the eye between the cornea and infinity)
the far point for this patient is located at the secondary focal point of the +2.00D lens, which is located at a distance of 1/2.00D=50cm. because the spectacle lens sits 15mm (1.5cm) from the cornea, the far point is 20-1.5cm=48.5cm behind the cornea (since this patient is a hyperope)
the following drops should be utilized for a cyclo refraction
- topical anesthetic
- 2 drops cyclopentolate
- 1% if >1yo
- 0.5% if <1yo
- phenylepherine or tropicamide for mydriasis
- perform refraction 30m later
cyclo in special population children
consider using only tropicamide 1% if a child has the potential for an increased reaction to cycloplegic agents, such as low birth weight, downs syndrome, cerebral palsy, trisomy 13 and 18, or other central nervous system disorders
a hyperope states that his single vision glasses work better when he pulls them further down on his nose for reading. How should his RX be changed?
increase in plus sphere
increasing the vertex distance of spectacle lenses will lead to an increase in the effective plus power of the lenses.
