Download Dear Notetaker:

BHS 212 – Ocular Physiology
Notetaker: Vivien Yip
Date: 08/14/2013, 1st hour
Page1
Questions regarding how to fill out yellow sheets for optometry lab
- Do not write abbreviations, i.e. CMA – Compound Myopic Astigmatism
- Line up numbers for assessment and plan i.e. 1. Allergic Conjunctivitis OU 1. Medication
Prescribed, 2. Compound myopic astigmatism 2. SRx released
- For every assessment, have to have a corresponding plan, don’t be wordy, just keep it complete
and concise
- On ocular page, write down the conditions regarding the eye, if unresolved leave date resolved
blank (repeat what you wrote down for assessments)
- Under systemic conditions, write down today’s date, diabetes x 4 years
- If no medications, allergies or systemic conditions: write none, do not leave blank
- NKMA or NKDA no known medical/drug allergies
Small Vessel Disease
High Blood Pressure – large vessel changes
Diabetes Mellitus (DM) – smaller vessel changes, elevated prostaglandin levels
Diabetes Pathophysiology
Pericytes – cells that support blood vessels, loss of support when loss of pericytes in DM, causes damage
to endothelium
Lack of oxygen causes neovascularization to try to bring oxygen in
Type 1 Insulin Dependent IDDM
Genetic predisposition
Usually occurs under age 30
Autoimmune rxn: destruction of beta cells that
produce insulin
Peak incidence at puberty
Tx: insulin, diet, exercise
Type 2 Non Insulin Dependent NIDDM
Primarily cases at IEI and practice
Strong genetic predisposition
Usually after age 30
Causes: cell receptor defect preventing glucose
uptake, decrease in insulin production from
pancrease, excessive glucose production from liver
Increase prevalence in blacks, Hispanics, Native
Americans
Frequently obese
Tx: diet, exercise, hypertension, oral meds
Diabetic Case History
- Ask pt everytime if diabetic:
o LBS, last blood sugar
o Glycated hemoglobin (HbA1c or A1c)
 Blood sugar average, aim for <7%
o Disease duration, when they were diagnosed
o Medications (oral type II vs injection type I)
Clicker Q:
A 45 yo pt presents with a medical history +ve for diabetes x 8 years. The patient takes 2 pills by mouth
per day and just began 1 injection after every meal for the condition, which of the following diabetes
classification best fits this pt?
1. Well controlled IDDM
2. Poorly controlled IDDM
3. Well controlled NIDDM
4. Poorly controlled NIDDM
Just began injections – this person has been on medications, not working, has had condition for a while,
need to step up treatment for the disease
BHS 212 – Ocular Physiology
Notetaker: Vivien Yip
Date: 08/14/2013, 1st hour
Page2
Ophthalmic Changes
- Chronic conjunctival injection
- Corneal curvature changes
o Water balance changes, difference in K readings
- Premature cataracts
o High levels of blood sugar can get more sugar in the aqueous leading to lens changes
- Cranial nerve III, IV, VI palsy
- Large fluctuations in refraction
o An issue when prescribing glasses, may change over short period of time
- Retinopathy
- Won’t see all of these in every patient
Refractive error
Spectacles and Contact Lenses
- Do not prescribe glasses for diabetic patient on first visit if it is not controlled, will have to
remake glasses
- Refer patient out to get them on medication for glucose control
- Do not prescribe glasses unless their blood glucose is stable
Please refer to these pictures below in colour online!
Subtypes of Diabetic Retinopathy
Non Proliferative – early stages
Dot/Blot hemorrhages
Lipoproteins, vessel leakage, vision not affected if in periphery
Edema – if in macular area will have visual acuity
White areas = cotton wool spots
Circumscribed exudates present
Maculopathy
Hypertensive – will not complain of changes in visual acuity
If condition affects the macula (edema or leakage) for DM – will affect vision
BHS 212 – Ocular Physiology
Notetaker: Vivien Yip
Date: 08/14/2013, 1st hour
Page3
If person is treated at this point (control blood sugar level), Leakage of vessel can be reversible
Vitreous is at the top
Indentation is the fovea on the left = Normal
Macular area is swollen on the right = abnormal, loss of acuity
If OCT is unavailable, can look at with a 90D lens and ophthalmoscope, see some changes in macula
Proliferative
Later stages of disease, more serious
Sight threatening stage
Changes around disc area, increased vessels
Retinal changes around the disc
Clicker Q
A new 60 y/o AAM presents for a CEE. (+) Newly diagnosed NIDDM (2 weeks)
All of the following information needs to be documented in the case history EXCEPT
1. LBS, last blood sugar
2. Glycosylated hemoglobin (A1c)
3. Breakfast that morning
4. Current meds
Retinopathy Pathophysiology
VEGF is separate from PKC, creates an increase in blood vessel growth
New blood vessels do not have proper support and are leaky, adding to the microaneurysm problem,
forming cotton wool spots and exudates
Clicker Q
Which of the following retinal findings is most likely to cause a reduction in a patients best corrected
vision?
BHS 212 – Ocular Physiology
Notetaker: Vivien Yip
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Date: 08/14/2013, 1st hour
Page4
Macular edema
Cotton wool spots
Micro aneurisms
Dot blot hemorrhages
Transdermal Pressure
TP = Pi – Po
Pi = pressure inside vessel
Po = pressure outside vessel
Summary
- Increase in PKC, leads to increase in VEGF
- Increase in Pi, leading to increase in transdermal pressure
- Vision loss comes later in the disease  proliferative
o Leading cause of vision loss, when people finally come in for an exam it’s too late to
reverse damage
Diabetes vs Hypertension
- DM does not necessarily have high BP
- Hemorrhage type: dot blot in diabetes
o Flame in hypertension
- Exudate pattern: more circular in diabetics
o Radial or star shaped in hypertension
- Fluctuation in refraction:
o Lens changes in water content
Clicker Q:
Hypertension in a large vessel disease, which of the following vessel types does diabetes have the
GEATEST affect upon?
1. Arterioles
2. Capillaries
3. Venules
Contact Lens technology
- Can test blood sugar levels via contact lens
- Measures changes in tear film glucose levels and changes colour of contacts
- Person can tell if blood sugar is elevated by looking at the contact lens
- Developing lenses with medication delivery
Bring blood pressure cuff and stethoscope to lab next week!