The American Journal of Medical Sciences and Pharmaceutical Research
41
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TYPE
Original Research
PAGE NO.
41-47
10.37547/tajmspr/Volume07Issue02-06
OPEN ACCESS
SUBMITED
13 December 2024
ACCEPTED
15 January 2025
PUBLISHED
17 February 2025
VOLUME
Vol.07 Issue02 2025
CITATION
Nikolay Pisnyy. (2025). Modern approaches to calculating parameters for
laser vision correction. The American Journal of Medical Sciences and
Pharmaceutical Research, 7(02), 41
–
47.
https://doi.org/10.37547/tajmspr/Volume07Issue02-06
COPYRIGHT
© 2025 Original content from this work may be used under the terms
of the creative commons attributes 4.0 License.
Modern approaches to
calculating parameters for
laser vision correction
Nikolay Pisnyy
Owner of MEDADVANCE company, consulting engineer at FOCUS clinic,
Almaty, Kazakhstan
Abstract:
This article examines existing technologies for
calculating the parameters of laser vision correction.
Achieving optimal results requires considering corneal
characteristics, including its shape, thickness, and
specific refractive abnormalities. The objective of this
study is to analyze the methods used to determine laser
correction parameters.
Techniques such as optical coherence tomography,
confocal microscopy, and multilayer corneal structure
analysis provide a comprehensive assessment of its
condition, allowing for the consideration of refractive
disorders such as myopia, hyperopia, and astigmatism
in determining laser exposure parameters.
The study demonstrates that technologies utilizing
mathematical modeling enhance the accuracy of
treatment outcome predictions. Three-dimensional
corneal geometry analysis contributes to the
predictability of surgical outcomes and minimizes the
risk of complications. These methods pave the way for
more effective vision correction techniques, positively
impacting patients' quality of life.
The presented material will be valuable to
ophthalmologists and developers of laser surgery
equipment. The findings confirm the necessity of
implementing methods based on individualized laser
exposure calculations, as these technologies enable
advancements in vision surgery and contribute to
improving the quality of medical services.
Keywords:
Laser vision correction, corneal topography,
laser ablation, ocular biometry, optical coherence
tomography, mathematical modeling, treatment
individualization, ophthalmology.
Introduction:
Laser vision correction plays a significant
role among methods for eliminating refractive errors.
The effectiveness of these procedures is determined by
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the precision of laser exposure parameter calculations,
which require consideration of factors such as corneal
shape, thickness, and the anatomical features of the
eyeball.
A personalized approach necessitates a meticulous
calculation of exposure parameters with a focus on the
anatomical characteristics of each patient. This helps
reduce the likelihood of complications and improve the
quality of functional outcomes. The use of topographic
analysis methods, biometric measurements, and
modeling enables the prediction of surgical results by
adapting parameters to individual characteristics.
Despite advancements in the field, the need remains
for the development of new methods to enhance
procedural accuracy.
Laser vision correction represents a medical field
where modern diagnostic techniques are being
developed, and advanced surgical technologies are
being implemented. Scientific studies in this area can
be categorized into several groups: methods for
myopia correction, techniques for astigmatism
treatment, approaches for intraocular lens parameter
calculation, and strategies for treating corneal diseases
using innovative tools.
Research focused on the treatment of myopia and
astigmatism emphasizes a personalized approach to
therapy. In a study by Zainutdinov N. N., Kamilov H. M.,
and Kasimova M. S. [1], the use of phakic intraocular
lenses for correcting high myopia is examined. The
study
highlights
the
necessity
of
selecting
individualized parameters that account for each
patient's condition.
Another study, conducted by Bikbov M. M. et al. [2],
investigates methods for addressing residual
astigmatism following cataract surgery. The research
focuses on surgical techniques and the selection of
optical parameters that minimize the risk of
undesirable outcomes.
In a publication by Belikova E. I. et al. [3], the features
of laser myopia correction in patients whose
professional activities involve continuous visual strain
are explored. The study underscores the importance of
considering accommodative characteristics during
surgical planning to prevent adverse effects.
Studies on intraocular lens parameter calculations
propose advanced approaches to minimizing errors.
Research by Holladay J. T. et al. [5] examines statistical
data processing techniques that reduce the likelihood
of errors in lens selection.
Wendelstein J. et al. [6] examine the effectiveness of
methods used for selecting lens parameters in
individuals with a short axial length of the eye. The
study highlights techniques that consider the
anatomical features of the visual system to improve
outcomes.
Scientific publications demonstrate the implementation
of new technologies for diagnosis and treatment. The
review by Shang H., Liu C., and Wang R. [4] presents the
potential application of computer vision to achieve
precise corneal surface measurements. This technology
enhances procedural accuracy and facilitates treatment
planning.
Another study by D’Oria F. et al. [7] explores comb
ined
approaches for treating corneal pathologies. The
publication provides a detailed description of
methodologies that integrate corneal cross-linking with
the implantation of corneal segments, improving their
effectiveness.
Source [8], published on the official website of Russian
Ophthalmology, presents calculations related to laser
vision correction. The obtained data were used to
describe the practical aspects of the procedure.
The reviewed studies identify several unresolved
challenges. These include the need to establish
standards for a personalized approach, improve
methods for calculating lens parameters, and refine
algorithms for the practical application of innovative
technologies. Despite significant progress, further
research is required to integrate new methodologies
into clinical practice.
The objective of this study is to analyze the methods
used to determine laser vision correction parameters.
The practical significance lies in the fact that the
implementation
of
the
proposed
approaches
contributes to better patient preparation and the
selection of treatment parameters based on anatomical
characteristics. This enhances procedural accuracy,
reduces the risk of complications, and improves
treatment outcomes.
The scientific novelty of the study lies in the
development of a methodology for calculating laser
vision correction parameters. The proposed approach
expands the scope of laser correction applications and
increases its effectiveness for patients with non-
standard vision parameters, such as thin corneas or
complex aberrations.
The working hypothesis states that the effectiveness
and safety of laser vision correction can be improved
through a combined approach that considers both the
optical characteristics of the eye and the biomechanical
properties of the cornea in dynamic conditions.
The methodology is based on a comparative analysis of
domestic and international scientific publications.
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RESULTS
Excimer laser-based vision correction remains a crucial
aspect of ophthalmology. Advancements in techniques
focus on optimizing laser exposure and developing
new computational algorithms necessary to achieve
stable outcomes. The correction of refractive errors,
such as myopia, hyperopia, and astigmatism, requires
consideration of multiple factors, including the
anatomical characteristics of the eye, pupil reactions,
and corneal properties.
Laser vision correction relies on a vast amount of data
obtained through high-precision diagnostic equipment.
Modern
approaches
prioritize
procedure
personalization. Mathematical models based on
wavefront analysis and optical concepts play a
significant role in these calculations [1, 5, 7]. Figure 1
below presents the approaches used for calculating
laser vision correction parameters.
Fig.1. Approaches to calculating the parameters of laser vision correction [1, 5, 7].
Application of Wavefront Technology. This method
allows for the analysis of light propagation through the
optical media of the eye, identifying defects that
require individualized correction. The use of this
technology enables the elimination of refractive
abnormalities and enhances visual quality after
surgery.
Special attention is given to optical defects associated
with various components of the ocular system.
Accounting for these factors improves the accuracy of
results.
Corneal Topographic Analysis. Corneal topographic
analysis is a critical diagnostic tool used to evaluate the
surface geometry of the cornea. By examining the
corneal surface, clinicians can precisely identify laser
impact zones and calculate procedural parameters for
refractive surgeries, such as LASIK or PRK. This process
involves the generation of detailed corneal maps,
which provide a comprehensive visualization of the
cornea's curvature, elevation, and thickness. These
maps enable the incorporation of individual
anatomical characteristics, ensuring a personalized
approach to treatment planning. The ability to account
for unique corneal features, such as irregularities,
astigmatism, or ectatic conditions, enhances the
accuracy and safety of laser-based interventions,
ultimately optimizing visual outcomes.
Optical Coherence Tomography (OCT). This imaging
technique is used to analyze ocular structures, including
the cornea, retina, and optic nerve. The method is based
on low-intensity infrared radiation and the interference
of reflected signals. In laser vision correction, OCT
enables the precise measurement of corneal
parameters, characteristics, and unique features while
also diagnosing pathologies such as keratoconus or
corneal thinning. The obtained results are utilized in
laser exposure calculations, ensuring a predictable
outcome with a minimized risk of complications.
Confocal Microscopy. This technique is used to study
the cellular structure of ocular tissues, allowing for the
assessment of epithelial and stromal layers, cell
distribution, and pathological changes. During the
preparation for laser vision correction, this approach
helps determine tissue condition and evaluate
regenerative capacity following the procedure [2, 3, 4].
Table 1 below outlines the stages involved in calculating
laser vision correction parameters.
Standard calculation based on refraction
Wavefront-optimized approach (Aberrometry-guided)
Topography-guided LASIK (corneal topography)
Lenticular extraction calculations
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Table 1. Stages of Calculating Laser Vision Correction Parameters [2, 3, 4].
Stage
Key Features
Indications
Method Advantages
1.
Initial
Consultation
Medical
history
collection,
visual
acuity
assessment,
identification
of
refractive
errors,
detection
of
contraindications.
Myopia, hyperopia,
astigmatism,
stable
refraction (at least 1
year).
Personalized
approach,
risk
minimization.
2.
Instrumental
Examination
Keratotopography,
corneal
thickness
measurement
(pachymetry), anterior-posterior
axis assessment (AXL).
Suitable for patients
with adequate corneal
thickness
and
no
corneal pathology.
High
diagnostic
accuracy
reduces
complication
risks
and
enhances
effectiveness.
3. Calculation
of Procedure
Parameters
Utilization
of
computer
algorithms and diagnostic data
to model laser exposure.
For
patients
with
unique
corneal
structural features.
Personalized
calculations,
high
precision, minimized
errors.
4.
Preoperative
Preparation
Prescription of eye drops for
corneal
hydration,
discontinuation of contact lens
use 1-2 weeks before the
procedure.
Recommended for all
patients
before
surgery.
Optimizes
corneal
condition for optimal
surgical outcomes.
5.
Laser
Vision
Correction
Corneal tissue ablation under
laser control (LASIK, SMILE,
PRK methods).
Suitable for myopia
up to -12D, hyperopia
up
to
+6D,
astigmatism up to
±6D.
Rapid
and
safe
procedure
with
minimal
tissue
trauma.
6.
Postoperative
Monitoring
Regular check-ups to assess
recovery, prescription of anti-
inflammatory and hydrating eye
drops.
Patients who have
completed
vision
correction.
Ensures eye health,
prevents
complications,
and
maintains stability.
The success of vision correction is determined by the
precision of calculations and the influence of external
and internal factors on the eye's condition after
surgery. Laser exposure induces changes in corneal
tissue, including its geometric and structural
properties. The prediction of these processes is
achieved using hybrid models that account for all
significant parameters.
To enhance calculation accuracy, data on corneal
thickness, elasticity, and tissue response are utilized.
This approach helps prevent complications.
Corneal thickness plays a crucial role in surgical
planning. Modern technologies accurately measure
this parameter, ensuring precise laser exposure and
reducing the likelihood of adverse effects.
A personalized approach to laser vision correction is
becoming a standard in ophthalmological practice. The
use of data on the anatomical characteristics of the
eyeball and the patient’s genetic predispositions
enables the development of individualized surgical
plans.
Genetic factors influencing corneal condition are
considered in outcome predictions. Integrating this data
into computational algorithms improves the accuracy of
results.
The postoperative period requires thorough monitoring
of corneal condition. Modern systems allow real-time
tracking of changes and adjustment of the recovery
process [1, 3, 5, 7]. For instance, trackers integrated into
laser systems detect even the slightest eye movements
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with high speed, automatically adjusting the laser
beam position. This ensures precise corneal ablation,
even if the patient cannot maintain a completely
steady gaze. After the procedure, monitoring systems
track the recovery process, analyzing dynamic changes
in corneal parameters. Table 2 below describes the
approaches used to calculate laser vision correction
parameters.
Table 2. Approaches to Calculating Laser Vision Correction Parameters [1, 3,
5, 7].
Method
Procedure Features
Advantages
Disadvantages
Future Trends
LASIK
Creation of a corneal flap
using
a
mechanical
microkeratome,
followed by excimer
laser reshaping of the
cornea.
Fast recovery,
minimal
discomfort after
surgery, stable
results.
Risk
of
complications
due
to
improper flap
formation, not
suitable
for
patients
with
thin corneas.
Development of
automated AI-
based
algorithms for
parameter
calculation and
improved
procedural
safety.
Femto-LASIK
A femtosecond laser is
used to create the flap
instead of a mechanical
microkeratome,
followed by excimer
laser reshaping of the
cornea.
Increased
precision
and
safety, suitable
for patients with
thin
corneas,
shorter recovery
time.
Higher
cost
compared
to
LASIK,
potential.
Integration with
diagnostic
platforms
for
full
procedure
personalization.
Super-LASIK
Customized
correction
program
based
on
individual
corneal
anatomy,
corneal
reshaping
with
an
excimer laser.
Personalized
approach,
improved visual
quality, ability
to
correct
higher-order
aberrations.
Requires
longer
diagnostic
procedures,
higher cost.
Development of
more
precise
corneal
scanning
technologies
and
the
implementation
of
neural
networks
for
data analysis.
Photorefractive
Keratectomy
(PRK)
Removal
of
the
superficial
corneal
epithelial layer without
flap formation, followed
by
excimer
laser
reshaping of the cornea.
Suitable
for
patients
with
thin
corneas
where
other
methods
are
contraindicated.
Longer healing
time,
postoperative
discomfort,
risk of corneal
haze.
Development of
new
corneal
epithelial
materials
to
accelerate
regeneration
after
the
procedure.
The process of determining the calculated value of
laser correction in Femto-LASIK for patients with mild
to moderate hyperopia to achieve the target refraction
is examined.
One of the key conditions for achieving high clinical
outcomes in Femto-LASIK for hyperopic patients is
reaching a postoperative target refraction within the
range of -1.0 to +1.0 D [8]. The optimal target refraction
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for hyperopic patients aged 25 to 30 years was defined
as a postoperative clinical refraction value under
pharmacological cycloplegia ranging from 0 to 0.5 D.
To achieve optimal target refraction in Femto-LASIK for
patients with mild to moderate hyperopia, a formula
for calculating the required laser correction must be
developed, taking into account the clinical refraction
values obtained under pharmacological cycloplegia
before the procedure. To determine this calculation
formula, a retrospective analysis of Femto-LASIK
outcomes was conducted in Group 1, which included
233 patients with mild to moderate hyperopia (233
eyes). The mean spherical equivalent of refraction
under pharmacological cycloplegia was 3.5±1.2 D
(M±σ). Figure 2 presents the distribution of target
refraction values after Femto-LASIK in patients of
Subgroup 1 (116 eyes, absolute success) and Group 2
(99 eyes, relative success).
Fig.2. Distribution of target refraction values after Femto-LASIK surgery in patients
of Subgroup 1 (116 eyes, absolute success) and in patients of Group 2 (99 eyes,
relative success) [8].
Figure 3 illustrates the distribution diagram of values
for achieving target refraction in Subgroup 1 (absolute
success) and Subgroup 2 (relative success).
Fig.3. A diagram of the distribution of values for achieving target refraction in the
subgroup with absolute success (1) and in Subgroup 2 (2) with relative success [8].
To determine the formula for achieving optimal target
refraction, clinical and functional outcomes of Femto-
LASIK in 116 patients of Subgroup 1 (116 eyes) were
analyzed. These patients achieved the target refraction
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of 0 to 0.5 D within 1
–
3 months postoperatively. Based
on this analysis, the following formula was developed:
𝑅𝑓
𝑡𝑎𝑟𝑔𝑒𝑡
= 𝑅𝑓
𝑚.𝑐.
− 𝛥𝐾
Where:
●
𝑅𝑓
𝑡𝑎𝑟𝑔𝑒𝑡
—
achievement of the
required level of target refraction;
●
𝑅𝑓
𝑚.𝑐.
—
initial clinical refraction
values under pharmacological cycloplegia before
surgery;
●
𝛥𝐾
—
keratometry change [8].
Thus, the specific features of calculating laser
correction parameters using the Femto-LASIK
technology for patients with mild to moderate
hyperopia, aimed at achieving precise target
refraction, have been examined. The developed
formula accounts for keratometric changes and
minimizes errors associated with accommodation,
thereby enhancing procedural accuracy.
The proposed method for determining laser vision
correction parameters is implemented through
structured stages, each designed to address specific
tasks. The diagnostic stage includes corneal
assessment, analysis of optical tissue characteristics,
and the detection of aberrations using wavefront
analysis techniques. Special attention is given to cases
involving anatomical corneal features that complicate
the application of standard calculation approaches.
The final stage focuses on verification and adaptation
of calculations. The methodology is based on modeling
data and previous scientific studies, allowing for
adaptation to various clinical cases, including
adjustments for patients with unique anatomical
features. The application of this method expands
access to vision correction procedures for patients who
were previously ineligible for such interventions.
Laser vision correction relies on a comprehensive
approach that integrates mathematical modeling,
diagnostic data analysis, and individual patient
characteristics. Modern techniques ensure calculation
precision, procedural safety, and predictable
outcomes. This approach improves treatment quality.
CONCLUSION
This study examined existing algorithms that
incorporate
corneal
topography,
biometric
diagnostics, and mathematical modeling. The findings
demonstrate high efficiency in selecting laser exposure
parameters, improving the accuracy of surgical
outcome predictions.
Technologies such as optical coherence tomography
and multilayer corneal surface analysis enhance the
diagnostic process by considering all relevant aspects
for ablation modeling. This approach reduces the
likelihood of complications and facilitates vision
restoration for various types of refractive disorders.
Collecting data on corneal parameters, including shape
and thickness, allows for precise treatment planning
tailored to each patient's characteristics.
The conclusions focus on improving methods for
calculating
laser
exposure
parameters.
The
advancement of technologies contributes to the
development of tools for accurate ablation parameter
selection, thereby enhancing treatment quality and
ensuring patient comfort.
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