presbyopia and more

Question 1

based on these NRA/PRA findings, what Add should be RXed for thus patient with a WD of 40cm?
NRA: +3.50
PRA: -1.50

Answer 1

+1.00D
an add can be determined by balancing the accommodative range within the NRA and the PRA values. the starting lens for am emerging presbyope for NRA/PRA testing is a tentative add or the distance RX

in order to balance the NRA and PRA to allow for half of the patient’s accommodative ability to be in reserve for comfortable vision, add the net NRA and PRA values together and divide by 2.
(+3.50 + -1.50)/2=+1.00D

Question 2

NRA

Answer 2

plus lenses are added in front of the patient at near until the patient reports the target is blurred

Question 3

PRA

Answer 3

minus lenses are added in front of the patient at near until the patient reports the target is blurred and can no longer be cleared. in a patient with presbyopia, the endpoint is the first plus lens that clears the print

Question 4

FCC

Answer 4

can be used to determine the appropriate add power for a presbyope, or to assess the accommodative response in a non presbyope

• the test is performed at 40cm with the JCC lens at axis 090 over both eyes through the distance RX or tentative add for a presbyope. no cyl power is dialed in. the patient views a target of two sets of lines that are perpendicular to each other. dim room illumination
• the horizontal lines should INITIALLY appear sharper (if not, reduce the room illumination). Add plus lenses slowly until the vertical lines are sharper, then reduce plus until both sets of lines are equally distinct and sharp (the end point of the test)

Question 5

expected findings on FCC

Answer 5

+0.25 to +0.75 for a non presbyopic patient, which represents the normal lag of accommodation. presbyopic patients will have higher level of plus power, depending on the age. This plus power is the add that should be RXed

Question 6

half amp method for determining add

Answer 6

as a general rule, the patient should have had the ampl of accommodation in reserve in order to maintain clear and comfortable vision. The theoretical add power is the working distance minus one half the patient’s amp of accommodation

Question 7

age based add power

Answer 7

40-42: +0.75
43-45: +1.00
56-57: +1.25
48-50: +1.50
51-52: +1.75
53-55: +2.00
56-57: +2.25
58-60: +2.50

Question 8

the patient has an amp of accommodation of 4.00D at a WD of 25cm to see fine details. what add power should be RXed?

Answer 8

+2.00D

Question 9

accommodative demand is equivalent to

Answer 9

reciprocal of WD

Question 10

what all changes happens during accommodation

Answer 10

• the ciliary muscle contracts
• tension is released on the zonular fibers
• the anterior surface of the lens moves forward
• the pupil constricts

Question 11

an emmetropic patient has a near point of 20cm. What add should be RXed for a reading distance of 40cm?

Answer 11

no add needed

Question 12

expected AoA

Answer 12

A=18.5-0.3(age)

Question 13

presbyopia

Answer 13

loss of accommodation with age due to loss of elasticity of the crystalline lens. Patients will complain of near asthenia and a decreased ability to meet their functional demands

Question 14

emerging/pre-presbyopia

Answer 14

generally beings when patients are in their early 40s and are starting to experience near symptoms

Question 15

functional presbyopia

Answer 15

there is a gradual decline in accommodative abilities, and patients required an add to comfortably perform near tasks. the power of the add is influenced by the patients age, functional demands, working distance, environment, ocular disease, and medications

Question 16

abolsute presbyopia

Answer 16

no accommodative ability remains