12. M IV - Non-Sx Correction & Management of Myopia II Flashcards
Ocular growth and refractive development are regulated by ... associated with the eye’s refractive status. From studies that involve foveal ..., it was hypothesised that the ... retina is influential in controlling eye growth. In normal myopic SVD corrections, peripheral ... is induced, which is thought to drive .... However, there are also studies that find that relative peripheral hyperopia ....
Ocular growth and refractive development are regulated by visual feedback associated with the eye’s refractive status. From studies that involve foveal ablation, it was hypothesised that the paracentral retina is influential in controlling eye growth. In normal myopic SVD corrections, peripheral hyperopic defocus is induced, which is thought to drive axial elongation. However, there are also studies that find that relative peripheral hyperopia does not predict development nor progression of myopia in children.
What are the two modes of myopic correction that can prevent peripheral hyperopic defocus?
- Flatten central cornea only e.g. OrthoK
- Increase (+) power in mid-peripheral cornea
Both induces myopic defocus in the periphery
Concentric ring bifocal SCLs have a central ... with ... of zones with ... e.g. ...D of simultaneous ... at distance and near. This forms two .... These contact lenses have different names: ..., ..., .... Children tend to ... for near, instead of using the concentric add zone like ....
Concentric ring bifocal SCLs have a central distance zone with concentric rings of zones with near addition e.g. 2.00D of simultaneous myopic defocus at distance and near. This forms two focal planes. These contact lenses have different names: Dual focus, Defocus-incorporated soft contacts, Bifocal contact lenses. Children tend to accommodate for near, instead of using the concentric add zone like presbyopes.
What were the findings in the study that compared dual focus CLs and MF CLs for myopia control?
There were slower rates of refractive change in dual focus CLs group compared to SVD group (0.4DS difference).
What were the findings in the first 3 years and subsequent 3 years studying MiSight CLs for myopia control?
First 3 years: Greatest difference occurred in the first 12 months of MiSight use compared to MF CLs. However, differences between groups sustained for the full 3 years.
Subsequent 3 years: Dual focus Cls continue to slow progression of myopia in children over 6-year period. However, rate of reduction slowed down.
Where were the visual quality difference between Dual focus CLs and Proclear MF CLs?
- Similar in high illumination and high contrast conditions in terms of VA
- Dual focus CLs had poorer VA in low-illumination and low contrast conoditions
- Dual focus CLs had lower patient reported outcomes: visual quality & ghosting
MiSight is available in:
* -...to-.. in 0.25DS steps
* -...to-... in 0.50DS steps
* No ... options
* Single ...
* Material: ... (...)
* Add = +...DS Recommended wear time: ... hrs+/day, ...days/week
MiSight is available in:
* -0.25to-6.00 in 0.25DS steps
* -6.00to-10.00 in 0.50DS steps
* No toric options
* Single BOZR
* Material: Omafilcon A (hydrogel)
* Add = +2.00DS Recommended wear time: 10 hrs+/day, 5-6days/week
Peripheral addition multifocal SCLs
* Central distance zone ...
Also known as a ... and ... control.
Peripheral addition multifocal SCLs
* Central distance zone + progressively increasing refractive power
Also known as a decentreed optical design and peripheral aberration control.
What were the findings in a myopia control study that compared high add power, medium add power and single vision CLs?
- High add was more effective than a medium add → 0.60DS increase vs -0.89DS increase
- Single vision CLs had the highest increase -1.05DS
Biofinity MFs available parameters:
* -... to -...DS in 0.25 steps
* -... to -.. in 0.50 steps
* ... options available in -... steps from -... to -...DC and available in ... degree axes step
* Single BOZR
* Material: ... (...)
* Prescribed as centre distance with +... near addition
Biofinity MFs available parameters:
* -0.25 to -6.00DS in 0.25 steps
* -6.00 to -10.00 in 0.50 steps
* Toric options available in -0.50 steps from -0.75 to -5.75DC and available in 5 degree axes step
* Single BOZR
* Material: comfilcon A (sillicon hydrogel)
* Prescribed as centre distance with +2.50 near addition
The average magnitude of reduction in myopia progression using MF and dual focus SCLs is ...D per year or ...mm/year axial elongation. However, most studies only followup for ...months. Most studies also included ... children with ... myopia (<...D).
The average magnitude of reduction in myopia progression using MF and dual focus SCLs is 0.20-0.30D per year or 0.10mm/year axial elongation. However, most studies only followup for 24 months. Most studies also included Caucasian children with low myopia (<3.00D).
Orthokeratology is originally designed to ... (.../ ...) during the day via a controlled .../ ... of the central cornea. The design of OrthoK contact lenses is called .... There are 4 different curves: ... curve (... zone), ... curve, ... curve and ... curve.
Orthokeratology is originally designed to eliminate the need for optical correction (spectacles/ CLs) during the day via a controlled remodelling/ flattening of the central cornea. The design of OrthoK contact lenses is called reversed geometry. There are 4 different curves: base curve (treatment zone), reverse curve, alignment curve and peripheral curve.
What were the findings in a myopia control study comparing OrthoK and SVD spectacles?
46% reduction in axial length increase in OrthoK treated eyes compared to SVD over 2 years.
Reduction of 0.50D/year over 2 years
What were the disadvantages of OrthoK found in studies?
- OrthoK users complaint of glare, aberrations and reduction in contrast sensitivity, however did not affect QoL overall.
- Risk of microbial keratitis similar to overnight CL modalities Risk of infection 7.7 cases per 10000, higher than daily SCLs and daily RGP wear, but lower than extended SCL wear.
- Mild SPK staining is the most common complication
What were the majority of the OrthoK microbial keratitis cases found to be associated with?
- Inappropriate lens design/ material
- Tap water for lens cleaning/ storage
- Lack of overseas industry regulation
What are the current limitations with OrthoK studies?
- Most small, single-site studies without randomisation
- Relatively small no. of trials
- Most studies Asian populations
- 2 year time period
- Biological mechanisms not clearly elucidated
- Rebound effect not extensively studied
What were the effects of peripehral aberration control spectacles (MyoVision by Zeiss) in myopia control studies?
- No significant reduction with aberration control spectacle lenses compared with SVD lenses over one year
- Younger children (6-12 years) with at least one myopic parent had small, but statistically significant, reduced rate of myopic progression.
DIMS stands for ... lenses. There is a ...mm optical zone for correcting ... Rx, which is surrounded by an annular ... zones with multiple segments (...mm in diameter) with a relative positive power of +...DS. The diameter of each segment is ...mm. This design simultaneously introduces ... and provides clear vision for the wearer at ... distances. These are also known as ... lenses, produced by .... The only material available is ....
DIMS stands for Defocus Incorporated Multiple Segments lenses. There is a 9mm optical zone for correcting distance Rx, which is surrounded by an annular multifocal zones with multiple segments (33mm in diameter) with a relative positive power of +3.50DS. The diameter of each segment is 1.03mm. This design simultaneously introduces myopic defocus and provides clear vision for the wearer at all viewing distances. These are also known as MiyoSmart lenses, produced by Hoya. The only material available is 1.59 polycarbonate.
What were the findings in a 2 year study with DIMS lenses?
Over 2 years, children assigned the DIMS lenses, on average, showed less myopia progression (~0.55D) and less axial elongation (0.32mm). There were no significant negative effect on VA.
HALT stands for ..., which consist of 11 ... formed by lenslet and create a 3D volume of .... It is also known as ... lenses made by ....
HALT stands for Highly Aspherical Lenslet Target, which consist of 11 concentric rings formed by lenslet and create a 3D volume of myopic defocus. It is also known as Stellest lenses made by Essilor.
What were the findings in a 1 year study and a 2 year study with HALT lenses?
At 1 year, children assigned HALT lenses, on average, showed less myopia progression (~0.53D) and less axial elongation (0.23mm). No negative impact on VA.
At 2 years, children assigned the HALT lenses, on average, showed less myopia progression (0.80D) and less axial elongation (0.35mm) compared to SVDs
Both DIMS and HALT have a ... in the centre of the lens, and a background of ... in the periphery of the lens. Both have a surrounding zone of ... to create differential ... across the retina, with spaces in between them for ... correction. Each behaves similar to single vision lenses that they do not alter ... like PAL or BF lenses. Both should be fit like a single vision lens, with careful attention to measuring the ... to ensure the child makes the most out of the ... for best acuity.
Both DIMS and HALT have a clear single vision distance zone in the centre of the lens, and a background of single vision correction in the periphery of the lens. Both have a surrounding zone of lenslets to create differential myopic defocus across the retina, with spaces in between them for single vision correction. Each behaves similar to single vision lenses that they do not alter accommodation or binocular vision like PAL or BF lenses. Both should be fit like a single vision lens, with careful attention to measuring the fitting height to ensure the child makes the most out of the clear central zone for best acuity.
What are the main differences between HALT and DIMS technology?
DIMS creates one plane on the retina due to the single vision zone of the lens, and another plane creating myopic defocus due to the +3.50D defocus lenslets. HALT creates a three dimensional volume of myopic defocus in front of the retina of vary dioptric power.
Dispensing criteria of MiyoSmart:
* Power Sph: 0.00 to ...; Max Cyl: ...D
* Central clear zone: ...mm in diameter
* Treatment zone: ..mm in diameter
* Defocus power: +...D
* Prescribed prism: ...pd per lens
Dispensing criteria of MiyoSmart:
* Power Sph: 0.00 to -10.00; Max Cyl: -4.00D
* Central clear zone: 9.4mm in diameter
* Treatment zone: 33mm in diameter
* Defocus power: +3.50D
* Prescribed prism: 3pd per lens
Dispensing criteria of HALTS/ Stellest:
* Power Sph: 0.00 to ...; Max Cyl: ...
* Material: ...
Dispensing criteria of HALTS/ Stellest:
* Power Sph: 0.00 to -10.00; Max Cyl: -4.00
* Material: 1.59 polycarbonate
